Last week I changed around my stereo a little bit just for fun and wanted to share a few of the things I learned in doing so. I didn’t do anything too crazy, just removed the Schiit SYS passive pre-amp and replaced it with a Denon AVR-1801 receiver. The receiver has been part of my garage theater which is currently undergoing some modifications. So I thought this would be a good opportunity to add it to my 2-channel stereo setup so I’d have an actual active pre-amp in the mix. Or rather, an active 5.1 receiver that happens to have a pair or RCA pre-outs (not something every receiver has these days I’ve come to find out) that should double nicely as a dedicated pre-amp. Acting as a pre-amp only the Denon holds its own quite well. A plethora of inputs, optical, coaxial, analog, even a phono input. Right now I’ve got two modest sources, an Apple Airport Express and a Sony DVP-S300 DVD/CD player. It’s worth mentioning that I bought the Sony unit from Goodwill for $6, the Airport Express from a guy on Craigslist for $20 and the Denon unit from a different guy on Craigslist for $50. Total investment at this point – $75. I do audio on the cheap, I know. But good gear doesn’t have to cost a fortune either. And good used stuff is even better.
Now back to the setup. Since the Denon has both analog and digital inputs, I was left with two connectivity options for each source: connect the CD player and Airport Express to the analog CD/DVD inputs using a couple pairs of RCA cables, or connect the S/PDIF or Toslink output from the CD player/Airport to the S/PDIF and/or Toslink inputs on the receiver. Either way you get sound coming out the other end. What difference would either option make? Was there not an obvious better way to connect up this equipment? If so, what was it? And was there a way to know which option would be better without actually listening to them?
So my first instinct was to connect everything up using only the digital interfaces. I figured the Denon probably has a better digital-to-analog path in it and therefore would sound better. This means the conversion to analog is bypassed on both the Apple Airport and Sony units to allow the Denon unit to do all the work. I have nothing against running analog in’s and out’s between stereo gear, but if you can keep things in the digital domain longer, and not flip flop between them too often, then it just seems like that should be better. Especially if you have reason to believe one of the two potential DACs and subsequent analog parts in your signal path is significantly better in one piece of gear than in the other. Imagine having two pairs of speakers connected to your amp via an A/B selector switch and selecting the crappier speakers all the time without even realizing it. Little did you know that just by switching to “speakers B”, you could have been listening to a much better pair of “speakers”, you just had to pick the better pair and put those in your signal path. Just about every stereo setup anyone owns probably has an unused DAC in there somewhere. Missed opportunity perhaps?
After connecting the CD player to the Denon via the S/PDIF port, I popped in some CDs and had a listen. Up until this point my setup was such that I was using the DAC in the CD player to convert the digital 1’s and 0’s to analog, but now I was feeding those same 1’s and 0’s to the Denon unit and allowing it to decode and convert those bits into analog sound. So what did I think? Did it sound better? Actually, my first impression was that it did sound better. Inexplicably better, not definitive, but somehow just better. Maybe I was just hearing things? Probably, but could I prove that one setup was superior to the other? Sure, why not? So I decided to do a little deep dive into the physical signal path differences between these two setups and compare them. What is actually different? Which configuration looks better on paper? What DAC chips are actually in these units? Were there other obvious defining differences? Read on to learn what I found out.
For now this is just going to be a paper analysis. I’m not going to actually measure anything. So if you’re hoping for FR and phase plots, THD and FFT plots, sorry to disappoint. But this is an easy analysis just about anyone can do with their own stereo, though your mileage may vary depending on which gear you’ve got, brand and how old (or new) it is. The internet is a huge resource, but even then, some old parts are just not going to turn up. And some of the newer and boutique audio shops just aren’t going to publish that kind of info. No sense revealing the Colonel’s secret 11 herbs and spices.
You can download a pdf of the information I put together for this chain analysis here which includes excerpts of schematics and block diagrams for both units. Datasheets for all of the components can be found by clicking the hyperlinks within this post.
I started out by searching for service manuals for both the Sony DVD/CD player and the Denon AVR. Service manuals are great for digging into this kind of thing and I found a ton of super useful information on both units. Such as schematics, part numbers, troubleshooting tips, you name it, these service manuals had it. That’s when the fun began! I traced out the digital and analog signal paths for each unit starting at the optical transport and finishing at the pre-out of the receiver. The one thing I was interested in initially was what DAC was in each of these units (but I actually learned quite a bit more). I was hoping from there I could then find out some specifications that might indicate which one should be better. My search didn’t stop at just the DAC though. But I’ll jump right into that part, since it’s the most relateable component. And if you don’t end up reading this entire article, you will at least have learned that much.
The Sony DVP-S300 contains a Sony CXD8750N-T2 2-channel DAC. There is absolutely zero information about this DAC available online. It is most likely one of Sony’s proprietary designs so they aren’t inclined to publish anything on it which means there’s no info out there to get any sense of what the DAC can do. Searching the part number online reveals that it appears in units with model numbers M35/S300/S305/S315/S500D/S705D/S715. So it was a popular DAC in its day used in a wide variety of now discontinued models. Not much else go go on there.
So let’s move on to the DAC in the Denon receiver. This is where it got a lot more interesting. The DAC in a Denon AVR-1801 is an AKM AK4527 “High Performance Multi-channel Audio CODEC”. AKM have been making DACs for ages and have a wide portfolio of DAC and DAC-related products. The the most interesting thing noted in the datasheet for the AK4527 is they claim it supports multi-bit. The first paragraph in the data sheet states,
“The DAC introduces the new developed Advanced Multi-Bit architecture, and achieves wider dynamic range and lower outband noise.”
There is no other mention of multi-bit in the rest of the datasheet and in most cases there are references to sigma-delta processing if it does come up again. I have no idea if this DAC does in fact support multi-bit as it’s commonly referred to today or not. This data sheet is dated 1999. Other specs tout 128x oversampling, 96 kHz sampling rate, 24-bit 8x digital filter, 106 dB S/R and high jitter tolerance. EEtimes.com wrote a short article about this DAC when it was released back in 1999 and here’s a short excerpt from that article:
“The six D-to-A channels use a new multi-bit sigma-delta architecture with 128X over-sampling. The dynamic range in this direction is 106 dB. This part brings a new performance level to multi channel codecs,” said Ahmad Nowbakht, applications engineer at AKM Semiconductor, a subsidiary of Asahi Kasei Microsystems Co. of Tokyo. He suggested the AK4527 could be used with compressed audio applications such as AC-3, DTS or other multi-channel standards. “It could be used in DVD players, DVD-RAM drives, or home audio receivers along with many other multi channel audio systems,” he added. The AK4527 is packaged in a small 44-pin LQFP, 10-x-10-mm, package with the same pinout as AKM’s previous two-input/six-output codecs. Prototype quantities are available now, priced at $6.12 each for 5,000 pieces.
So there you go, what’s the real takeaway? That they use the term multi-bit and sigma-delta in the same sentence? Like, which is it? How about the fact that this is a $6 DAC? Either way, if I had to blindly pick a DAC in my setup, either the Sony unit or the AKM unit, based on the information available, I’d probably pick the AKM DAC over the Sony DAC just because it’s got some decent specs against a part that has, well, no specs. It offers good dynamic range with 24-bit/96 kHz processing whereas the Sony DAC probably only supports 16-bit/44.1 kHz audio, seeing as how it is designed for a regular CD player, ideally there’s no reason for anything higher. Besides the bit depth and sample rate, are there other less obvious sonic benefits to one DAC over the other? Perhaps other features built into each chip make a larger difference, like better digital filtering, better tolerance to jitter, better DC biasing (power supply and power supply filtering) and better analog filtering. Specs alone hardly tell the whole story. But it’s certainly a starting point.
So what else did I learn about the signal path in my search? Let’s take a look at the op-amps. Both the Sony and the Denon filter the analog DAC output via a pair of standard operational amps. Likely configured in a simple low-pass filter and some form of gain stage to bring the output to line-level standards. The Denon service manual was scanned in with too poor a resolution to really tell what resistor/cap values are used. But that’s what the Sony op-amps were configured for. The Denon uses a pair of NJM2068 low-noise op-amps which are designed for high-performance audio applications. The Sony contains NJM4558V op-amps which are basically spec’d for general purpose applications and they don’t claim to be low-noise or suited for high-end audio applications. In fact, I thought it was funny that the datasheet for the NJM2068 claims it is actually better than the NJM4558. Ha! The two op-amps I have in this very setup. Must be a popular pair? Here’s an excerpt from the datasheet below:
“The NJM2068 is a high performance, low noise dual operational amplifier. This amplifier features popular pin-out, superior noise performance, and superior total harmonic distortion. This amplifier also features guaranteed noise performance with substantially higher gain-bandwidth product and slew rate, which far exceeds that of the 4558 type amplifier. The specially designed low noise input transistors allow the NJM2068 to be used in very low noise signal processing applications such as audio pre-amplifiers and servo error amplifier.”
So the op-amps in the Denon are “sold” as being better than the ones in the Sony. Okay, fair enough. A/B comparing the datasheets reveals identical equivalent circuitry, with the exception of one extra cap on the NJM2068 across the gate input of one of the transistors. Perhaps one of the means by which they claim lower noise? Here’s some other features that favor the NJM2068 op-amps in the Denon; better common mode rejection and power supply rejection, faster slew rate, higher bandwidth, lower noise voltage and they actually spec THD at 0.001% whereas the NJM4558V doesn’t spec it at all. I’ll take a good spec over no spec any day.
So once again, on paper, the Denon op-amps appear to be the winner in this signal-path shootout so far. So to sum up what we found: the Denon has a presumably better DAC and definitely better spec’d analog op-amps than the Sony. If if you had to pick which signal path to choose, would you choose the Denon or the Sony? For now I am thoroughly enjoying allowing this old $6 Sony DVD/CD player to act as a transport-only thus allowing the Denon unit and its superior AKM DAC and NJM op-amps to decode and process the digital and analog signals. It sounds great to me, though mainly I just enjoy knowing what parts lie between the player and the pre-outs. It’s surely just a placebo effect by me visualizing the signal running through some crappy Sony DAC and a couple of 69 cent op-amps compared to the signal being fed to a decent AKM DAC and NJM audio-grade op-amps (don’t look up how much they cost though). My brain is telling me one path is better than the other. I guess I’m just a dork like that. But wait, I’m about to dork out even more on this. I wasn’t satisfied just tracing out the digital to analog portion of the signal path, I wanted to trace out the entire signal path, from CD to speakers. Here’s the jist of what I learned, starting with the optical pick-up all the way to the speakers. Buckle up, we’re in for a wild ride.
The Sony DVP-S300 contains a KHS-180A/J1N optical transport. One that was used in a vast array of Sony units back in the day. A guy on Ebay sells them for $165 a pop because apparently it’s the same unit used in the Sony SCD-777ES and SCD-1 Super Audio CD Players. Units that sold for $2500 in their heyday. Hey cool, not a bad find for $6 at Goodwill. We’re starting off with presumably a half-way decent optical pickup and if you get right down to it, the optical pickup/transport is really only responsible for one thing, getting information off the disc optically and converting it into an electrical format with which the rest of the electronics can actually process/amplify/filter/decode as appropriate. This signal from the optical block looks nothing like you might think, it’s not really a digital signal at all, it’s a modulated RF signal! Using a modulation type known as eight-to-fourteen (EFM) the “bits” coming off the disc form an eye pattern but don’t actually look like 1’s and 0’s yet at all. Check out the patent for more information on the subject. Pretty interesting stuff!
In the Sony unit the modulated RF signal feeds what’s called a “CD RF AMP”. The model number is CXA2555Q-T4. I found the datasheet for this unit and what it does is basically amplify, filter, and EQ this RF signal in preparation to send it off to the ARP unit for demodulation (it performs other functions like laser tracking and focus). The next part in the signal path is the ARP unit, model number CXD1865A. This device is actually responsible for demodulating this crazy-looking eye pattern RF signal (that yes, contains our audio signal buried inside) and creates a binary data stream into two much more common formats: S/PDIF and I2S. Aha, now we’re getting somewhere. We all know what S/PDIF is and many fewer of us are familiar with I2S but at this point we at least have an intelligent digital data stream that represents audio from the CD with bit-for-bit-accuracy. But is it really bit-for-bit? We haven’t even got to the DAC yet but how confident are we that we have a digital representation that actually matches what is on the disc? My take is this, and I could be wrong, but demodulating a NRZI or EFM encoded compact disc is not new, in fact, every CD player in every computer you’ve ever owned is capable of demodulating every bit off that disc with perfect precision, because it was designed to do just that. Here’s a quick excerpt from one of the service manuals on the details of just what’s inside the ARP unit:
“In the ARP, first RF signal processing such as asymmetry correction, adaptive equalization, and sync clock extraction by the RF-PLL are carried out so that the signal becomes binary data synchronized with the PLL clock. This data is…EFM demodulated (CD-DA and video-CD) in the demodulator, subjected to frame/sector sync detection, address detection, and protection, and sent to the buffer memory controller.
…This is the same for the CDDA. The ARP is linked to the built-in and external memories, and CDDA signal processing block to carry out error correction, output data flow control, etc. The signal is then muted and corrected by the CDDA signal processing block, and then sent to the IC203AV decoder (L64020).
For all of these disks, RF jitter is calculated by the RF signal processing block, and this information is used for adaptive control of the servo DSP via the CPU.”
Forget about what DAC you’ve got, I want to know what ARP you’ve got! I can’t even figure out what ARP stands for. There is no datasheet out there for the CXD1865A. I don’t hear a lot of talk on the street about this fancy demodulation and error correction device either. Seems like it’s pretty dang important though. I think most people just think everything is 1’s and 0’s, all the time, I know I did, until I started researching this whole signal path thing. Kinda feels like I fell into a rabbit hole a little bit though. Did you know that a CD is actually an analog medium? Yeah, stew on that for minute or two. Do we even know what digital really is?
Some things worth noting about what goes on this ARP unit, and presumably every single CD player out there, is error correction and jitter management. When I read about people using a CD player as a transport, such as the way I am using it in my system, you are effectively removing as much of the processing of both digital and analog signals as you can and offloading that work to an external DAC but you’re still dependent on at least two IC’s in that “transport/CD player” to create a perfect binary representation of what is on that disc. EFM modulation contains error correction. The engineers at Sony and Phillips knew that an optical disc being read by a laser would be susceptible to errors, so they created a modulation pattern with built-in error correction, much like almost every data transferring scheme developed in the modern world today. Nothing gets through perfectly every time, errors occur, through various means, and when they do, there has to be a mathematical means of re-creating lost data. And a way to do it perfectly. But what happens when too much data is lost? And what constitutes too much lost data? And if data is lost, what is reconstructed in its place? The ARP unit is responsible for all of that (and more) and yet it’s never mentioned in most stereo systems.
I think I’ve lost track, let’s circle back to another day. You can check out this site if you want to read more about this topic or this site here for some really good general info on the compact disc. For now let’s assume we have all-new, pristine CDs with no scratches, damage, pits, or other defects that would otherwise make that ARP have to do more work than necessary and heaven forbid, actually have to make up stuff that isn’t on source medium. Let’s follow the signal paths of our two signals, we’ve got S/PDIF and I2S at this point coming from the ARP where both signals are fed to the AV Decoder part number L64020-D-QC-27. I was able to find the datasheet for this device and the only noteworthy thing I took out of it is that is passes the S/PDIF and I2S signals straight through without any additional processing. The signal names bounce around a bit in the schematic, and they never call these digital signals “I2S” by name but presumable it meets the interface standard because all there are 3 data lines that track throughout the circuit and the signal names are _DATA, _BCK and _LRCK which coincide with I2S naming convention for a multiplexed data signal, the bit clock and left-right clock. So it’s definitely I2S. Might there be a way to pipe this out directly to the MiniDSP? Hmmm, a topic for another day.
The S/PDIF signal is fed to a TC7S08FU AND gate then to a simple transistor buffer stage before terminating into a standard female RCA plug (and don’t forget the orange center plug!). So surprisingly not much going on there and very little processing to get from the compact disc surface to something we can finally start to decode and turn back into an audio signal. In short working backwards, the S/PDIF signal comes from the AV Decoder (bypassed) which is fed by the ARP unit which demodulates the EFM signal from the RF AMP which amps, filters and EQ’s the RF signal from the optical block which is using a photo sensor to pick up the pulsing pattern of a laser beam bouncing off the surface of the CD encoded with pits and lands that make up a digital representation of audio. Wow. And this my friend is ~36-year old technology. As complicated as it is, it’s amazing. The time and energy that was put into developing the standards behind the audio compact disc in a day and age where computers as we know them today did not even exist. It boggles the mind that you can seriously walk into any Goodwill and find a half a dozen old CD/DVD players selling for under $10. It’s just crazy.
Alright, let’s go back to my original analysis, let’s follow the I2S path and see where it takes us. The I2S standard, unlike S/PDIF is not really meant for long runs or runs in cables between stereo equipment. It requires 3 signal lines plus ground and is more suited towards internal interconnects either on single circuit board between devices or between boards with very short runs where impedances can be controlled in order to maintain good signal integrity. I won’t get into the I2S specification, you can download it online. It was developed by Phillips back in 1986 and they describe it as follows:
Standardized communication structures are vital for both the equipment and the IC manufacturer, because they increase system flexibility. To this end, we have developed the inter-IC sound (I2S)bus – a serial link especially for digital audio.
Hey, we all like common interface specifications, it just makes things so much easier to mix and match and let hobbyist and hardware developers do what they do best. So back to the Sony DVP-S300, the I2S signal is fed to the infamous nothing-can-be-found-about-this Sony DAC, the CXD8750N-T2. The DAC without a name or any information available online. C’mon Sony. Okay, so to be fair, this thing is old as mud, I’m not surprised there isn’t any info out there. We’ll just assume it’s a run-of-the-mil digital-audio converter with 16/44 bit/sample rate just good enough for your average Joe. The DAC output feeds the two NJM4558V op-amps which look to be configured as a low-pass filter and a gain stage similar to the Denon. The second op-amp likely bumps the output level to standard line-level and then over to the pair of RCA jacks. And that’s our analog output path from the Sony CD player. Tracing back to the split-point between the S/PDIF and the I2S we can see that the only real difference between the digital out on this unit and the analog out is one DAC and two op-amps. Which is exactly how it should be, and which is probably how most CD players are architected.
This post is a million miles long, man how did I get here? I haven’t even traced out the digital and analog paths within the Denon unit yet! So let’s finish off the analog path in the Denon receiver where we left off coming out of the DAC and from the NJM2068 op-amps to the actual pre-outs on the back of the receiver. And then we’ll come back to the digital path from the S/PDIF input. And lastly we’ll talk about what the analog path looks like coming into the receiver, such as through the CD input and I’ll tell you why you should never trust the analog CD input on a home audio AV receiver like this for 2-channel audio. You probably already know, but I won’t ruin the surprise.
So back in the Denon the analog signal from the NJM2068 op-amps following the DAC is fed to a switch which provides selection of different sources (since it’s a receiver with like 8 inputs). The part is a Toshiba TC9162 Analog Switch Array. Noteworthy specs are 0.001% THD and 1.0 uVrms noise voltage. Frequency response looks like it extends to 50 kHz, though they don’t spec it directly. The device is probably as transparent as any analog switch and sort of a necessary evil if you want more than one source. Which brings us to the volume control. I was happy to see that the volume control is done completely in the analog path and that it is digitally controlled. The chip is a Toshiba TC9482 which is designed to be used as a volume controller in high-end audio equipment. It basically incorporates a resistor array that offers 95 dB of range in 1 dB steps. THD is spec’d at 0.005% and noise voltage is 1.2 uVrms. BW is not spec’d though test conditions indicate 20-20kHz and there’s no indication of amplitude flatness.
So the volume control is sort of another necessary evil. One could design the volume control in the digital domain, but then you run into issues with dynamic range and using the “total available bits”. And I don’t even want to get into that whole discussion. After the volume control, there’s another NJM2068 op-amp. Man these things are everywhere inside this unit! I guess if you’re going to design a receiver, might as well pick a decent op-amp and just litter it everywhere you need one. Keep the unique BOM count low and get the best price breaks on a single device. Oh and the NJM2068 you can buy for only 60 cents. 45 cents if you buy 50 or more. If you’re Denon and buying thousands of these things, they probably get them for a quarter or less. Yes, that’s what audio-related electronics cost in the commercial world. Like I said, the dollar value consumers associate with a piece of audio gear does not always reflect its actual value or the true cost to manufacture it. But anyway, moving on…
Following the NJM2068 op-amp, the signal splits, one path feeds yet another NJM2068 op-amp tied in with a Tone Control device which is a Toshiba TC9184. The other path bypasses both the op-amp and the tone control device. A switch on the other end allows the tone control to be “defeated”. A nice feature for the “purist” who doesn’t want either the option to adjust bass and treble thus ensuring a perfectly flat response, or because defeating the device all together makes you feel better about the signal path, that you’ve somehow eliminated some unnecessary extra circuit. Sure, you can just set both the Bass and Treble knobs to “0” but is that really the same as clicking the fancy “Tone Defeat” switch?
Turns out it’s not the same. Well at least it’s not a gimmick, the switch does in fact defeat the tone control chip and supporting components, so if there were even the slightest hint of degradation caused by the part, it would be defeated as stated. I run with the tone defeat switch on because, well, I simply enjoy knowing that this little extra bit of circuit is not part of the signal path and I don’t really need to add additional bass or treble boost since the MiniDSPs are already configured for a flat in-room response. No sense mucking all that up with course bass and treble knobs. But even then, looking at the datasheet for the TC9184 it’s about as transparent as can be. It’s basically a massive ladder array of different value resistors in conjunction with passive external low and high-pass filters that are then summed with one of the NJM2068 op-amps. But it’s a digitally controlled part, though the entire the signal path is all analog and mostly passive. Specs for the tone control part state typical THD of 0.005% but no other noteworthy parameters for the signal path otherwise. My guess is the tonal quality within this path is probably more heavily influenced by all the caps used in the filter network than the bulk array of resistors. But you can see, setting the Bass and treble knobs to “0” is not the same thing as hitting the “tone defeat” switch from a signal path perspective. Now ask me if I can tell the difference between the two? Nope. Not one bit. Unless either of the bass or treble knobs is adjusted any amount off of “0” since the step size is a whopping ±2 dB. That I can hear.
Anyway, that’s about it. The signal goes from the tone defeat switch straight out the RCA pre-outs and then, in my setup, off to the pair of MiniDSPs, the Emovita UPA-700 and then finally to the DM-4 speakers. I’m not going to trace out the signal path any more than this for today. I’ve gone on far enough that you get the idea. Ultimately the signal that we just spent so much time converting to an analog is going to be converted once again back to a digital signal in the MiniDSP, where it will be processed digitally (performing filtering, EQ, gain/attenuation and delay) before it’s converted back to an analog signal for the last time. After all this you can understand why there’s a case for not having an active crossover/DSP unit in this location in the signal path. The extra ADC-DAC conversion feels unnecessary and some may say sets an “upper limit” or boundary of sorts for how good my system will ever sound. Nothing will ever sound better than the weakest link in your setup. I’m not saying the MiniDSPs are not great, they are awesome little units, but a part of me is itching for a pair of the new MiniDSP HD 2×4 units. At least the MiniDSP does support I2S, so it’s possible to skip the extra AD conversion, unfortunately my setup doesn’t really support doing so in this manner, and since MiniDSP (the company, not the product) discontinued the MiniDIGI, I’m not quite sure how to improve this setup beyond just replacing the MiniDSPs one day or attempting to tap into the I2S directly off the CD player. But once again, a topic for another day.
The last thing I wanted to share is why after researching this why you should be careful using the analog “CD/DVD/VCR” inputs with an AVR in a 2-channel setup. The reason? Because the analog signal is most likely being converted back to digital for additional DSP. In my setup the analog inputs eventually make their way over to the AK4527 DAC (which actually has a 2-channel ADC in it as well) before being converted back to analog. That’s right, there is one more ADC-DAC conversion for those inputs. Though it’s not clear what settings on the receiver invoke this path, because there’s another path the goes straight from the analog inputs the Switch Array TC9162 device, joining back up at the same spot where the AK4527 DAC feeds. So as long as you can guarantee that you haven’t hit some button on the receiver (like all the fancy surround sound modes, Pro Logic or music effects that are included, blah) that causes the signal to be fed back into the AK4527, then the signal path stays all analog from input to output.
However just be to sure, the best all-analog path is the 5.1 inputs since those are fed directly to the switch array and bypass all other digital devices in this AVR, thus eliminating even the option to accidentally re-encode-decode the signal by selecting some special sound mode. So for fun, imagine the worst-case setup – the signal path if we used the analog outputs from the CD player (that’s one DA conversion) to the CD input on the receiver set to a fancy sound mode where it’s converted back to digital and then back to analog (that’s two DA conversions plus one AD conversion) and then is fed out to the MiniDSP where it’s converted back to digital-from-analog, processed via DSP and the converted back to analog (that’s two AD conversions and now three DA conversions) before being amplified and fed to the speakers. It sounds terrible on paper, I know, all those conversions back and forth and back and forth from digital to analog to digital etc., though I honestly wonder, would anyone be able to tell the difference? I might try out some A/B tests of such a setup, because it would be pretty easy to do.
And that pretty much sums everything up for this episode of Decoding My Signal Path. In the end it was a fun exercise and as I begin my hunt for additional audio gear, I’ve realized that unless I can find this level of detail in the components within the components, I’m not satisfied just relying on reviews from folks claiming the ability for a particular piece of gear to make music sound like pink fluffy unicorns dancing on rainbows. I want cold hard facts man. And I only looked at signal path and didn’t even consider biasing paths. I could dive deeper into this, and I know there’s people out there that do. They redesign input/output stages or swap op-amps, change out capacitors, add supply filtering, add shielded inductors, you name it, people have done it. Until then, happy listening! And if you’ve got a setup similar to mine, let me know how you’ve got it connected and what you like about it. See ya!