Generalized attributes of amplifier technologies

Well, many SS amps have in excess of 50 Khz BW.  Most transformers do not. They are by definition an inductive LP filter.  What is up there is only harmonic distortion. This is not a bad thing, only a difference.  I am not suggesting roll-off in the classic audio band as even the 6W Chinese wonder chassis I built a Red Light Special on  held up pretty well into the mid teens. I do see McIntosh has continued to make transformer improvements extending their BW.  Kind of their hall-mark! The current ones seem to sound less "classic tube" to me than the earlier ones though I know amps like the old CJ or Dyna better. Could be transformers, could be larger grid isolation resistors. I am sure the higher quality passive components help a bunch. 

MOSFET amps sound different from BJT. They all can measure what single tone lab testing says is inaudible and I agree that with a 1K tone, I hear no difference and if I did, I would blame it on the speaker that is probably in the .3 or .4% range there.  Unfortunately, that is only part of the story. If it was, My Fosi V3 would be the killer amp.  Fine in my garage but I put it on my main system for a lark and with music it fell flat on it's face. Terrible distortion at what had to be less than 10W. This also  brings up why on earth we can hear tiny differences with music in electronics when the speakers are 100 times worse?  What is our brain doing!? Toole does not yet and if He doesn't, for sure I have no clue. But we can. 

Single tone measurements are valid, but limited. MOSFET amps, or at least the majority that are based on the original Erno B. Hitachi design ( mine is highly modified but similar character) all have a false smoothness to them while beating the dynamics of a BJT .  General rule may not hold to the Atoll which in a store sounded more BJT than I expected and the Hegel sounded more FET-ish. 

I have three DACs right now. All with classical measurements as one might see on ASR  should be well, make that way,  below audibility. They should sound identical. They do not.  I have some suspicions on the implementation and on how they handle certain input signals that explain some of it. Reducing through JRiver -3 dB did make them sound much closer, close enough I question if I hear differences between two of them, so digital cliping from filter overshoot may well be a valid issue. I note RME and Chord both deal or at least talk about that. Pre-ringing and the amount of post ringing from the various filter algorithms may be related. I have an idea that may be a lot of why some prefer R2R NOS DACS . 

I recently saw a suggestion that some class D and A/B handle broad band noise differently. This may be only in the dirt cheap range of class D and fully resolved as is load invariance in the current higher quality units. Hypex, Purify, maybe ICE. Not picked up in two tone IM measures. 

The point is, from these generalizations and more I am sure I am missing, can we extract some parameters that may eventually lead us to a multiple attribute plot with subjective preferences we could graph devices on using objective measures?   If you are a detail freak, pick from this quadrant, if buttery midrange, pick from that quadrant . More weight and so on.  We need to quantify what causes these attributes to measure them. We could then design to them. 

Generalizations are a place to start. I'm retired and not designing another amp.  My goal is to get some thought that may lead someone else further down the road so maybe I can buy the fruits. What can bring the classic objective measure camp and the pure subjective camp to common ground?  Both right, both wrong. 

So do I buy the Vidar, Buckyeye or Denafrips amp?  Keep searching for a Stasis 7?Am I thinking of it with only nostalgia? Aragon? Older Classe?  Early Cary? Or are my old 60's and 70's music remastered on early CD so crappy I should stick with my Mosfet? If I get it wrong, the level of domestic distortion will skyrocket. 

Not meaningless, as it follows under innovation. Improvement in application we will have to see, but yea, an omission that we should watch.   Unfortunately, still quite rare and expensive only in boutique products as of yet.    Hmmm, seems Peachtree has a product.  I had ignored them as until now, I hated every one I heard for classic "Digitates".  I need to track one down.  Progress I hope!

Looked up the Peachtree GaN400.  Specs wise, mid-range so that makes it into probably "need to listen" for the other half of the sound.  I see they still make the old 500 that I did not like.  

VTV is an interesting product but as I only have USB, not viable.  I would have a lot of questions about their D2D front end. It is probably the way of the future.  The only DAC being the output stage. Less can be more.  Falls under innovation for sure. 

Curious side note.  In every class D amp I have seen internals of, the output networks are ferrite core and electrolytic caps , yet we go to great length and expense to remove them from our speakers.  Something to investigate. 

Atmasphere, 

If you read my post, I said exactly that. A general statement and some did better. Most did not. I have a hard time believing 100K though. 

Also agree, the distortion profile is driven by the topology. Going to large grid resisters "hardens" the sound of a tube. David Manley demonstrated this. The myth of even or odd harmonics is purely a topology factor even in a tube amp. SE vs P-P if I remember.  I can miss-balance the LTP of a SS amp and get high even harmonics. I sold my tube books so I can't give you a direct reference. Cordell and Self did talk about even vs odd in their SS books. 

And absolutely! Execution is often more important than the technology.  My generic statements refer to well executed. You can screw up the best parts and technology. 

For innovation, I was just looking at the Sajab amplifier.  It takes in the USB data stream,  processes in DSP for level eq.,  generating the PWM it feeds to the output class D stage. So no conventional DAC in the front end. Only the integrator on the output.   This makes sense to me. How it sounds I haven't a clue and have not seen traditional objective specs. 

Maybe why the old Cary OTLs sounded so nice.

Yea, thanks for the reminder on topology. I forgot which was which.