Differences in sound: DAC vs. DAC + Pre-amplifier

[barrows]

@Audiophile Neuroscience, I am not a "believer" in amplifiers being "better" just because they cost more.  I have heard all the usual suspects at shows, Soulution, Audionet, Vitus Audio, etc, etc,  All of those amps sound good, but I hear nothing in their performance which is not offered (or even bettered by, in some cases) a pair fo Mola Mola Kalugas.  A few of the mega expensive amps have been heard on the same speakers as the Mola Mola as well (Alexia 2 or Giya 2/3).  I hear (sometimes) slight difference with all of these amps, but none of those differences amount to anything which I would term "better".

 

IME, these days, there is no benefit anymore for the best class A amps vs. the best class A/B amps, as the crossover distortion problems have been solved by good engineering.  Given the insane waste of energy of class A, I consider them bad engineering at this point, as they offer no benefit anymore, at least not that I can hear. 

 

And then there are the obviously colored amps at mega prices, such as DartZeel, where the measurements show distortion products at what are clearly audible levels.  There are those who prefer such amps, which is fine with me, but one is gong to have problems if suggesting they are accurate.

 

Of course superb sounding amps can built DIY, and at a fraction of the cost of the usual mega expensive amps.  Something like DartZeel for example, has already been cloned by DIYers: of course they will not usually have the mega expensive chassis work!  I do not have a problem with the existence of high 5 and 6 figure amplifiers, as long as the buyers understand that they are paying for exclusivity, and very expensive custom case work, and not better sonics: transistors, resistors, capacitors, transformers, and some wire and PC boards only cost so much!  This is similar to very expensive watches, they do not tell the time any more accurately than something one can buy for $15.

 

As for class D, I view it the same way as all other classes of amps: there are a few good class D amps, and there are many bad ones.  Bruno Putzeys Ncore designs are the "best", at least until his new Purifi amps become more available.  As Mr. Putzeys has mentioned many times, his designs are not good because they are class D, they are good inspite of being class D.  He acknowledges that it is very difficult to engineer good sounding class D amps.  I never considered class D in the top tier of amplifiers until the Ncore designs were released, and Mr. Putzeys has now improved on Ncore with his Purifi design work (I am currently building up a Purifi based amp).  The Mola Mola is a tweaked Ncore design, and I suspect well implemented Purifi based designs to be better (at least measure better, whether the difference will be audible is remains to be seen).

 

When I said "absolute best", I believe I was referring to tube vs solid state there.  Of course there is no "absolute best" as how a given amplifier interacts with a loudspeaker differs, especially with some esoteric designs which may not be compatible with all speakers.  

 

My conclusion on amps, given what I have heard, is that one never needs anything more expensive than Mola Mola (OK, 5 figures there, although there are alternatives which should sound as good for $3K, i just have not heard them, same modules, and similar implementation).  Sure, one can spend much, much more, and get an amp which might sound slightly "different", but not actually better.  I feel we are at a point with electronic development where things are getting very close to "perfection" in terms of transparency and any differences which are actually audible are mostly down to slight colorations, rather than more or less transparency to the source.  My advice to people building systems these days is to spend the big money on loudspeakers, as the big differences in performance are there, and shop carefully for electronics, do not believe the hype, and do a lot of listening.  Class D amps save money because they do not require large enclosures, large transformers, or large heatsinks, this is smart engineering.   As for loudspeakers, well, they are expensive because really good enclosures are necessary for the best sound quality, and largish speakers are necessary if one has a decent sized room, so one cannot get around the fact that really good speakers are going to cost some cash-as mentioned previously, I think Vivid Audio has a leg up here, as they have applied molded composites in their cabinet construction which allows them to produce very good cabinets at fraction the cost of some of their competition (Magico, etc).  The expense of loudspeakers is going to stay the same, at least until there is some kind of major breakthrough in the science (pulsating spherical plasma drivers or???) which would eliminate the need for large, non-resonant, boxes.   

[Foggie]

 "you are preferring is the addition of distortion products...... If one prefers a colored sound, rather than an accurate one, that is fine with me"

 

So the reverse to this statement or preference could be, if ones prefers a sterile, fatiguing, and hi-fi sound which equals "accurate", go with Class D and no tubes, no pre amp, no class A etc... 

One can call distortion, coloring whatever you want because the very nature of using those terms triggers an immediate compromise which is false IMO / IME.  In reality, doesn't every component color, distort somewhere in the chain (audible or inaudible).  Even/odd ordered harmonics..........

Really this has been debated for a gazillion yrs, just like cables etc...It is impossible for anyone to claim that components "x y z" are really all that is needed, sound the best, everything else is colored and therefore "inaccurate".  Everything is a compromise and more importantly we all hear differently and make decisions based on that.

I'm in no camp but my own. When I demo'd components in my rig, those experiences made me change and rebuild my rig from scratch because they proved to be more real, accurate etc.. what sounds best to me.  Go figure.

 

Be safe, and happy listening to all

[barrows]

6 minutes ago, Foggie said:

So the reverse to this statement or preference could be, if ones prefers a sterile, fatiguing, and hi-fi sound which equals "accurate", go with Class D and no tubes, no pre amp, no class A etc... 

Totally disagree.  It appears that you believe the function of an audio playback system is to imprint its own sound on the recording, editorializing on what the musicians and engineers intended.  I have no problem with that, as long as you accept it as well.

That is not what I am after, I prefer a playback system which is faithful to the sound of the recording, and does not add a "sound of its own".

 

BTW, I do not find an accurate playback system to sound "sterile, fatiguing" in any way (unless of course the recording is, and bad recordings do exist).  I would suggest that you are confusing an accurate sound with one that is colored.  I doubt it is the intent of musicians and recording engineers to produce recordings which are sterile and/or fatiguing sounding, and neither do i find that truly accurate playback systems sound as such (with good recordings).

 

Simple put, accurate does not equal sterile and fatiguing, accurate means warm sounding recordings will sound warm, a fatiguing sounding recording will sound fatiguing.  It means the playback system gets out of the way of the music.  Perhaps you have never heard such a system?  As an example of such, i would suggest you have a listen to the following:

 

Mola Mola Tambaqui DAC (or Makua preamp with DAC), Mola Mola Kaluga mono blocks, into some Vivid Audio Giya G-1, 2, or 3 loudspeakers, or Wilson Alexia 2s.  i have heard this set up, and/or similar ones a few times.  It is very detailed, even extremely detailed, but I find it totally natural sounding as well, with no fatigue.  In the past, especially with digital playback, there have been some annoying artifacts in playback, and systems which add some color of their own were often preferred for their ability to reduce the impact of the artifacts by obscuring them-the problem being that this color also obscured valuable musical details.  With the best electronics available now (especially DACs), we have entered a new realm of playback, where it is no longer necessary to obscure artifacts to reach acceptable playback sonics, as the annoying artifacts themselves have been eliminated.

[Foggie]

I stated "preference could be" in a sort of hypothetical. 

 

Unless one was in the control room or live room when it was recorded, no one knows what a "specific" album sounded like and everyone tunes their rig based on their liking, preferences, experiences.  My reference is my background in playing instruments

 

I'll respectfully disagree.  Good luck. 👍

[barrows]

17 minutes ago, Foggie said:

I stated "preference could be" in a sort of hypothetical. 

 

Unless one was in the control room or live room when it was recorded, no one knows what a "specific" album sounded like and everyone tunes their rig based on their liking, preferences, experiences.  My reference is my background in playing instruments

 

I'll respectfully disagree.  Good luck. 👍

Right, we disagree!  BTW, i do not need an accurate reference to know what "sterile fatiguing" sound is.  

As far as references go, I totally agree, and even started a thread at these forums about references:

 

 

BTW, my GF is a professional performing and recording musician.  And I have been present on occasion to her laying down tracks in the studio, hearing the monitor feed, and the subsequent recordings, both as rough mixes, and finished versions.  I also hear her in rehearsal and practice, playing and singing un-ampliifed, as well as performing amplified, etc.  These are pretty good references, especially for female voice.  I try and play a little myself, but I basically suck at music, she is quite talented though, with a lovely voice.

Anyway, I am not at a loss as for an idea of what some music should sound like.

[Audiophile Neuroscience]

8 hours ago, barrows said:

@Audiophile Neuroscience, I am not a "believer" in amplifiers being "better" just because they cost more.

 

 

Neither am I. IMO better amps are better because they sound ......better, closer to the real thing (as discussed above in this thread). IME that is pure class A amps, and yes they are expensive.

 

8 hours ago, barrows said:

 

 I have heard all the usual suspects at shows, Soulution, Audionet, Vitus Audio, etc, etc,  All of those amps sound good, but I hear nothing in their performance which is not offered (or even bettered by, in some cases) a pair fo Mola Mola Kalugas.  A few of the mega expensive amps have been heard on the same speakers as the Mola Mola as well (Alexia 2 or Giya 2/3).  I hear (sometimes) slight difference with all of these amps, but none of those differences amount to anything which I would term "better".IME, these days, there is no benefit anymore for the best class A amps vs. the best class A/B amps, as the crossover distortion problems have been solved by good engineering.

 

I agree, If you cannot hear any improvement then it would be silly to spend money on a more expensive amp.

 

8 hours ago, barrows said:

 Given the insane waste of energy of class A, I consider them bad engineering at this point,

 

Yes but they keep you 'toasty' in winter ! 😁

 

8 hours ago, barrows said:

  I do not have a problem with the existence of high 5 and 6 figure amplifiers, as long as the buyers understand that they are paying for exclusivity, and very expensive custom case work, and not better sonics: transistors, resistors, capacitors, transformers, and some wire and PC boards only cost so much!  

 

Well, not SQ that you can hear and that is fine. So your generalization " as long as the buyers understand that they are paying for exclusivity, and very expensive custom case work, and not better sonics" applies to you, not everyone.

 

8 hours ago, barrows said:

When I said "absolute best", I believe I was referring to tube vs solid state there.  Of course there is no "absolute best" as how a given amplifier interacts with a loudspeaker differs, especially with some esoteric designs which may not be compatible with all speakers.  

 

With respect you seem to make generalizations and then qualify them later.You explained this earlier by saying you expect people to assume certain things about your generalizations. Would it be more prudent not to make the provocative generalizations in the first place...and as @sandyk pointed out, not paint yourself into a corner?

 

 

 

8 hours ago, barrows said:

I feel we are at a point with electronic development where things are getting very close to "perfection" in terms of transparency and any differences which are actually audible are mostly down to slight colorations, rather than more or less transparency to the source.  

 

Yes, we have discussed this theory before and you are certainly entitled to it.

 

8 hours ago, barrows said:

 

 

My advice to people building systems these days is to spend the big money on loudspeakers, as the big differences in performance are there, and shop carefully for electronics, do not believe the hype, and do a lot of listening.

 

and presumably they shouldn't listen to any "hype" whether about speakers or electronics. My advice is to listen to the music played by all the components. IME the better the electronics and their implementation, the better the speakers will sound.

 

 

8 hours ago, barrows said:

 Class D amps save money because they do not require large enclosures, large transformers, or large heatsinks, this is smart engineering.   

 

No argument, just for me, they do not sound as good or accurate or transparent as top class A amps (YMMV). The caveat,as before, I have not heard Mola Mola or purifi.

 

8 hours ago, barrows said:

As for loudspeakers, well, they are expensive because really good enclosures are necessary for the best sound quality, and largish speakers are necessary if one has a decent sized room, so one cannot get around the fact that really good speakers are going to cost some cash-as mentioned previously, I think Vivid Audio has a leg up here, 

As an owner of Vivid G2's I must agree 😉

[davide256]

On 3/30/2020 at 1:17 AM, Audiophile Neuroscience said:

 

 

I have not heard Mola Mola Class D amps but are you saying they sound better than, or just as good,as, the best Class A amps? The "Absolute best" ?

 

IME absolute best sound quality for my ears has been pure class A SS amps and yes, they are expensive. YMMV. Having said that, I fully accept there is a law of diminishing returns and as said, I have not yet heard Mola Mola up against the best Class A amps.

 

But I have also heard good DIY class A designed amps that sound excellent without costing an arm and a leg.

Unfortunately class A amps are also "space heaters" 😉 Heard anything you like near 50 watts other than Pass?

[Kimo]

On 3/30/2020 at 11:56 AM, barrows said:

 

IME, these days, there is no benefit anymore for the best class A amps vs. the best class A/B amps, as the crossover distortion problems have been solved by good engineering.  Given the insane waste of energy of class A, I consider them bad engineering at this point, as they offer no benefit anymore, at least not that I can hear. 

 

 

 

 

 

Could you please elaborate on the modern new exotic engineering revolution that has magically made crossover distortion disappear?  I think some of those bad engineers like Nelson Pass would be interested in learning how to improve their designs.

 

 

[barrows]

54 minutes ago, Kimo said:

 

Could you please elaborate on the modern new exotic engineering revolution that has magically made crossover distortion disappear?  I think some of those bad engineers like Nelson Pass would be interested in learning how to improve their designs.

 

 

This is not news, or anything new.  Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

I suppose you do realize that Pass Labs makes both Class A and Class A/B amplifiers, right?

 

Please do not put words in my mouth, I did not call anyone a bad engineer, and certainly not Nelson Pass who I have an enormous amount of respect for.  

 

I find statements such as the above inflammatory (and maybe emotional?) and not conducive to good discussions in any way, perhaps you might like to re-think your approach.

 

As to excellent class A/B designs with low levels of distortion, I suggest you might have a listen to a Bricasti M-25 or anything from Constellation, perhsps...

 

I used to own a Pass Labs, class A/B amplifier, but after quite a few direct comparisons, over the course of a year, i ended up preferring my DIY Ncore based amplifier, this experience was turning point for me.

[sandyk]

1 hour ago, barrows said:

Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

  A better than average Class A/B amplifier may sometimes equal a typical Class A amplifier in performance, but a well designed Class A amplifier  will still outperform it.

 

A quote from Douglas Self in Audio Power Amplifier Design Handbook 5th ed - D. Self (Focal, 2009)

Quote

Class-AB
This is not really a separate class of its own, but a combination of A and B. If an amplifier is biased
into Class-B, and then the bias further increased, it will enter AB. For outputs below a certain level
both output devices conduct, and operation is Class-A. At higher levels, one device will be turned
completely off as the other provides more current, and the distortion jumps upward at this point as
AB action begins. Each device will conduct between 50% and 100% of the time, depending on the
degree of excess bias and the output level.
Class-AB is less linear than either A or B, and in my view its only legitimate use is as a fallback
mode to allow Class-A amplifiers to continue working reasonably when faced with a low-load
impedance.
Class-B
Class-B is by far the most popular mode of operation, and probably more than 99% of the amplifi ers
currently made are of this type. Most of this book is devoted to it. My definition of Class-B is that
unique amount of bias voltage which causes the conduction of the two output devices to overlap
with the greatest smoothness and so generate the minimum possible amount of crossover distortion.

 

[Audiophile Neuroscience]

6 hours ago, davide256 said:

Unfortunately class A amps are also "space heaters" 😉

 

They sure are.

 

6 hours ago, davide256 said:

Heard anything you like near 50 watts other than Pass?

 

@sandyk how many watts is your class A amp?

 

I do like the Nelson Pass but for me they have a slightly warm signature overall, unlike for example Gryphon.

[Audiophile Neuroscience]

2 hours ago, barrows said:

 Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

You do seem fond of  generalizations

 

2 hours ago, barrows said:

I suppose you do realize that Pass Labs makes both Class A and Class A/B amplifiers, right?

 

Porsche make a range of different models to suit their customers too.

 

2 hours ago, barrows said:

Please do not put words in my mouth,

 

With respect, people are not "putting words in your mouth", just responding to the words you put in your mouth

 

2 hours ago, barrows said:

I did not call anyone a bad engineer,

 

just "bad engineering"

 

2 hours ago, barrows said:

 

I find statements such as the above inflammatory (and maybe emotional?) and not conducive to good discussions in any way, perhaps you might like to re-think your approach.

 

🙄

 

2 hours ago, barrows said:

I used to own a Pass Labs, class A/B amplifier, but after quite a few direct comparisons, over the course of a year, i ended up preferring my DIY Ncore based amplifier, this experience was turning point for me.

 

and i am sure we are all glad you are enjoying your path.Please let others enjoy their path without some sort of condescending subtext or generalizations that imply your path is best (let alone "absolute best").

 

Stay well

[Kimo]

2 hours ago, barrows said:

This is not news, or anything new.  Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

I suppose you do realize that Pass Labs makes both Class A and Class A/B amplifiers, right?

 

Please do not put words in my mouth, I did not call anyone a bad engineer, and certainly not Nelson Pass who I have an enormous amount of respect for.  

 

I find statements such as the above inflammatory (and maybe emotional?) and not conducive to good discussions in any way, perhaps you might like to re-think your approach.

 

As to excellent class A/B designs with low levels of distortion, I suggest you might have a listen to a Bricasti M-25 or anything from Constellation, perhsps...

 

I used to own a Pass Labs, class A/B amplifier, but after quite a few direct comparisons, over the course of a year, i ended up preferring my DIY Ncore based amplifier, this experience was turning point for me.

 

Nelson and I are still waiting for an answer to the question.  The guys from Benchmark might be curious to learn how this all works as well.  Seems like they spent a lot of effort trying to eliminate crossover distortion.

 

I imagine there are posters here that can answer for you, but you keep pushing them away.  Maybe, you should shut up for awhile and let those guys talk, so we could all learn something here.

 

 

[sandyk]

1 hour ago, Audiophile Neuroscience said:

sandyk how many watts is your class A amp?

 Hi David

 My Class A Amplifier is 15W/Ch into 8 ohms, and >30W Channel in Class B,(which is better than Class AB) into 4 ohms, in which case it remains in pure Class A until around 7.5W.

 It dissipates around 80W of heat at a Bias of 1Amp, and due to the size of the 2 side heatsinks it doesn't get too hot for my cat to sleep on top of in Winter.

 I have never been able to use it at full power in a typical sized room of a modest sized house,( e.g. a converted double bedroom)  but it would obviously be too low a power for high level sound output use in much larger dwellings.

 With TV Audio for example, a typical output level is around 1W

 

Regards

Alex

 

[sandyk]

1 hour ago, Audiophile Neuroscience said:

I do like the Nelson Pass but for me they have a slightly warm signature overall, unlike for example Gryphon.

 

 I noticed that too.

They probably use MOS FET output stages, or FET input stages.

Perhaps both ?

[craighartley]

On 3/19/2020 at 8:07 PM, barrows said:

Wow Craig, 39 dB is really high and quite unusual gain for a power amplifier.  Have you ever contacted the manufacturer and asked if the gain could be lowered?  That much gain is probably also make the amp(s) noisier than they could be.

 

Of course your "click" problem is something other than preamp related.  If i had that "click" problem i would track down the ideal solution for the problem, rather than covering it up by adding a transformer based pre/volume control.

Barrows, I wonder if you could help me please? If I am in right in thinking that you use Sonore Rendu (linux) native DSD, to a DSC-2 DIY DAC, with Amanero firmware CPLD_1081 slave and 2006be11, can you please confirm you have no clicks (muting problems) when playing direct to power amp with software volume control?

 

I am told that that firmware is likely to be the source of the clicks I have using the T+A DAC 8 DSD (streaming DSD) direct to power amps. 

[MhtLion]

In my experience, low to mid range (who knows what is the actually boundaries in terms of price but let's say under $3k) preamps were better without. Pretty much all my DAC's (even $300 one) with a volume control provided me with a better results without a preamp for my ears. But, with higher end preamps - they still loose some resolution/micro details to my ears, but they usually had a great synergy with their own brand power amps. So, to me it was a toss up between a better tonality vs micro details. But, I have turntables. So, I just needed a preamp at the end of the day. That being said, I wish the next generation DACs will have a variable impedance. 

[SoundSparks]

Dear experts:
I have been following this fruitful discussion closely and found it very informative. My experience auditioning Lindemann musicbook:10 DSD in two quality setups (PASS Labs and Simaudio MOON power and pre) clearly demonstrates I was unable to distinguish reliably DAC direct vs. preamp mode. It “seems” I preferred DAC direct in PASS setup, and preamp mode with Simaudio MOON. I can offer no explanation here, unfortunately enough…

[Abtr]

On 3/29/2020 at 2:24 PM, motberg said:

What do you guys think about adding sub-woofers in a DAC direct to amp system?

Is it OK to split a 2V RCA output and run a set of cables 1 meter to the amp, and another set to the subs maybe 4 meters each?

 

I get the feeling that most DAC makers generally are expecting the user to use a single set of outputs to a single receiving device.

 

 

In the past I have used a pair of Y-connectors to split the RCA output of DAC/preamp to power amp and powered sub, both with an input impedance of 10kΩ, giving a combined load of 5kΩ for the preamp. Then I used the built-in active line-level 2-way crossover of the sub and it all sounded significantly better. I later learned that the system still was really quite far from optimal.

 

Apart from avoiding a possible impedance mismatch between DAC/preamp and multiple parallel power amps – which may at first sound transparent but which actually sucks the life and dynamics out of the music – IMO one needs a good quality crossover to integrate front speakers and sub. I tried passive line-level crossovers (PLLXOs) but these introduce all kinds of problems which are dependent on input, and output circuitry, and IME they always sound suboptimal. I much prefer an active crossover approach for both ease of use and sound quality; properly bi-amping front speakers and sub can have a large positive impact on SQ. This implies that I must use at least one active line-level circuit (the crossover) between DAC and AMPs, i.e., a preamp.

  

Now, apart from expensive pro-audio active crossovers there are not many commercial options for a simple, good quality active crossover for sub(s) and front speakers, operating at a given crossover frequency. MiniDSP is a very versatile solution which I may try but I don't particularly like the idea of an extra AD/DA conversion and I understand overall sound quality is not to write home about, which may largely be a problem of the analog output stage and/or the power supply.

 

Currently I use a pair of Xkitz Xover-2 units which implement a high quality (audiophile), fully analogue, 24dB/octave Linkwitz-Riley line-level crossover, with OPA1654 opamps that exquisitely drive my power amp and powered sub. I must say that I did replace the LM317-based power supply of the Xkitz boards with a power supply based on ultra-low noise and low impedance LT3045 regulator chips, which brought the SQ to a level that I find quite amazing.

 

On topic: A lesson I've learned is that the quality of the power supply and analogue output of any preamp is of crucial importance for sound quality. And IMO a preamp can indeed sound very good but it cannot improve the source signal. If DAC-direct sounds worse than DAC + preamp then there must be a problem with the DAC's  analogue output and/or power supply.

 

Good luck!

 

[Abtr]

By the way, I agree with @barrows and don't quite see how a preamp could improve the output of a DAC. If the analog output stage and/or the power supply of a DAC/pre is a problem, then there's simply no way an additional preamp could fix that. So if you use a separate DAC and preamp then the power supply and analog output stage of *both* DAC and preamp need to be of good quality. 

[The Computer Audiophile]

I’ve had some strange issues lately that we’re resolved by putting a preamp between the DAC and amp. I don’t like that this was the resolution, but it was. For example, one DAC had very audible pops when using specific filter settings and switching sample rates. These were inaudible when using a preamp. 

[Abtr]

21 minutes ago, The Computer Audiophile said:

I’ve had some strange issues lately that we’re resolved by putting a preamp between the DAC and amp. I don’t like that this was the resolution, but it was. For example, one DAC had very audible pops when using specific filter settings and switching sample rates. These were inaudible when using a preamp. 

Is this apparently digital distortion dependent on the DAC's volume control? Do you have DAC side attenuation disabled or at max volume when using the preamp?

[The Computer Audiophile]

1 minute ago, Abtr said:

Is this apparently digital distortion dependent on the DAC's volume control? Do you have DAC side attenuation disabled or at max volume when using the preamp?

It’s frustrating to me because analog isn’t my specialty. I wish I understood what was going on. 
 

yes, the DAC was set to max digital volume with a preamp. I’m unsure if the pops would’ve been present if set to max volume without a preamp. Don’t have the guts to try that one. 

[audiobomber]

18 hours ago, Abtr said:

Now, apart from expensive pro-audio active crossovers there are not many commercial options for a simple, good quality active crossover for sub(s) and front speakers, operating at a given crossover frequency. MiniDSP is a very versatile solution which I may try but I don't particularly like the idea of an extra AD/DA conversion and I understand overall sound quality is not to write home about, which may largely be a problem of the analog output stage and/or the power supply.

There are miniDSP solutions that don't require an ADC. The SHD has one analog and several digital inputs and contains two DAC's, as well as digital coax outputs in case you want to use an outboard DAC (or two). The analog output stage was designed for miniDSP by a well-known DIYAudio member and is supposedly quite good. The minDSP SHD Studio is D-to-D only, no AD or DA converters. They have recently added a new model with inboard power amp.

 

The above come with a built-in streamer and Dirac license. 

https://www.minidsp.com/products/shd-series

[barrows]

24 minutes ago, The Computer Audiophile said:

I’ve had some strange issues lately that we’re resolved by putting a preamp between the DAC and amp. I don’t like that this was the resolution, but it was. For example, one DAC had very audible pops when using specific filter settings and switching sample rates. These were inaudible when using a preamp. 

Chris, that sounds like DC problem at the DAC output.  If the DAC exhibits DC problems like this, a preamp will sometimes eliminate them before they get to the AMP, as the preamp will have DC correction of some type (servo circuit, I believe int he Constellation gear).  Sometimes DACs will have a DC spike in between locking... a properly designed DAC "should" be muting its output to avoid this in between locking to new sample rates.  I have seen this in DIY DACs a bit, where we might not have the most sophisticated control software.  Raising the buffering in Roon can sometimes help this.

Of course, for a DAC designed to connect to an amplifier directly this would be considered a fault of the DAC design and the manufacturer should address it.