My NAD 3020 D proves your Class D tropes are wrong

@jwl244, I have auditioned an NAD c298 which uses purifi tech. I had this powering a set of martin logan 60xti. I was using my naim uniti atom as a preamp. They sounded really really good. I tried doing side by side comparisons with the naim uniti itself powering the speakers. This isn’t a fair comparison as the atom is only 40 wpc. However, playing both at high (Not ear splitting) levels I was able to detect a subtle difference. I could be biased as I do love the naim sound. However, I found the NAD to be a bit too clinical in its presentation compared to the naim which was more lively and easy to listen to although not overly warm. The NAD was VERY clean but almost to a fault. I did use TIDAL. I do think class D is the future whereas class A and AB have kind of hit a wall as far as growth and expansion. Class D still has room to grow.

jwl244,
I’m familiar with the amp and the 60xtis. Two questions, did you try the c298 amp with any other speakers, and how many hours did you have on the amp before pulling it back out of the system you were listening to?

btw, I’m a Class A, A/AB amp owner, potentially looking for a smaller footprint type class-D amp to test with different speakers i design and build. I’m following experienced listeners trying amps with the newer Purifi modules. Wondering how far you took your listening sessions with this particular amp. Thanks in advance for added details you might be able to share.

@jwl244 I am curious in your opinion and others in this forum...Is one possible reason we lean away from class D because of its distortion profile or lack thereof? My understanding with the best class D and purifi products distortion is really low.

Possibly. I find dedicated solid state class-A amp owners may tend to be more forgiving of traditional Class-D sound thinking about "heat" and "weight", and yet Tube amp owners not as much at first (maybe liking some distortion, with 2nd and 3rd order harmonics); however some hard-core tube amp owners may like the idea of rotating in another amp to spare their prized tubes on rotation, or like the idea of less heat over the hotter months of the year. Reasoning and conditions vary by individuals we can suspect. All a guess, I’m simply trying different things when I can.

And, to your first point, silly me went over to the Audio Science Review (ASR) forum and started asking if "anyone" had tried pairing up a really good tube preamp with the NAD C298 Purify module based amp. Quickly realized all measurement extremists over there, few wanting to engage into "sound" discussion or anything with higher distortion. Felt like a single alien against an army of thousands of pure scientists only focusing on measurement. Stupid me, I still want to try a really good 6SN7 tube preamp in front of a NAD c298 class-D amp just to see what happens.

A few great measuring amps and ruler flat speakers I’ve heard in my system were some of the most boring and non-engaging to my ears. Blame my room and/or blame my ears, the difference was notable to my ears. I like a little distortion in the right places.

Distortion: Something on that same type wavelength. I evaluated an ultra high-end solid state DAC a few years back, 125db SNR, amazing build quality, amazingly huge sound stage. Clear, smooth, deep in detail, yet it was one of the more fatiguing and un-engaging pieces of equipment in my particular system. Was kinda shocked. "All the notes, none of the music". Then one month later swapped back to my more distorted R-2R ladder DAC with a musically distorting tube and all the "music" and engaging layered three dimensional sound returned. Wallah, back to listening to music instead of listening to components. Recently heard a very nice higher $ class-D ice module based amp at a buddies house. He left it on for 3 days before I got there. I’m not sure if we agreed it was missing some of the harmonics. He later went with a dual tube R2R DAC, and it helped some however it is not able to produce a layered and 3-diminensional sound that I’m more use to. Smooth, somewhat musical, and 2-D at best. I think I’ve listened to class-a and tubes for too long and we all formulate our opinions on what sound good to us or perhaps leaning more towards the familiar sounds we started with or grew up with.

If you follow Paul @ PSAudio, hard core solid state guy for several decades since his time at Krell, recently accepting hybrid tube front-end BHK designs paired into their mosfet amps. Who’d a thunk, it happened. Then he opened up to Class-D. Who’d a thunk, it happened again. Even Paul reports publicly Class-D is going to be something to recon with (even more so), with added designs and development "over the next 5 years". I’m not totally "there" yet willing to continue to experiment as options evolve a bit more. Its exciting to see more rapid progress past 2-3 years with class-D, and eventually I plan to own a good Class-D amp. Looking for a great "keeper".  AGD has done some neat things... Also, kinda waiting for the right sounding hybrid design to surface. I’m betting we’ll see more coming from purist SS & Tube manufactures, realizing they have no choice now but to accept Class-D like PS Audio did, and doing well at it.

@jwl244,
"@decooney I wish I could say I put a ton of time in. I may have listened here and there for less than 20 hours total in a few weeks. I did not switch speakers in or out."

Good to know. Barely scratching the surface of end-game potential, possibly. I won’t name the company, yet the owner of a different Co started wondering why they were getting more returns than ever anticipated on a solid sounding product. After some in-depth internal investigation ,something very telling surfaced for this Co. They instituted a (3x) much longer pre sale/shipping burn-in process to these particular class-D products and components. The customer returns dropped radically after this process was introduced. Then they tell the customer to give it another 100-200hrs for the final 5%. Not all, but some higher-end gear benefits from longer burn in cycles, finally reaching a set point, optimum specs, bias, and maybe the type of sound we all look for. Its definitely worth giving a try in the future, fwiw. Good luck.

I enjoy how Nelson tries different output transistors within his stash, in different circuits he comes up with in his head. Admittedly, 1 of 10 of those variations actually make it to production. He intentionally looks for rare or extinct opt transistor supplies to make it harder for people to clone his amps. Each variation and release sounding different from the past. Exploration never ends with him. Just gotta love it, rinse and repeat with new Opt's. All in search of a new and different variations of "sound" amplification.

I seriously doubt the majority of the self-proclaimed scientists over at the ASR forum have proper tools and platforms to measure all the various aspects of sound. Clearly many over there don’t use their ears much either, simply looking at graphs, charts, specs, produced by limited tools measuring only a few aspects of sound.

A fun read for those who appreciate the nature and physics of sound, so much more to it than a few metrics and specs used by techs too, have yet to see an audio lab covering much about sound https://physics.info/sound/