I'm not happy with the treatment of the supply wiring routing. All the wires are just floating there, never the return current twisted around the send..lots of loops.
jn
Thanks John.
It was much more a quickfire answer I was after really... JC's best 100, Sonys best (as you hear them) 80, 90 whatever, or maybe its less than that, or perhaps they come much closer.
OK, one of my examples. A typical £$300 CD player vs a £$1000 one of my choosing. My chosen player, I score it as 100/100, the others, maybe as much as 93 but that difference is everything... yes. To me its worth the price premium. A portable at £$20. That might get to a 85 or higher. If I had 10k to spend on a player it might push that 100/100 to 102 and thus become my new reference. Would it be worth ten times the price tag... hmmm maybe not to me.
So your amp choices... what sort of differences are we talking when you change cabling, change passives etc. Is it 100 becomes a 100.5 and thus your "new reference". Or are the differences much more than that to you...
Its not going to work this I can tell 
1968, a great year for me! I was still mostly using discrete parts, with a few RTL IC's for my motor drive servo, developed the complementary differential input stage, and started on my quest for low noise design with the QuanTech that we had in the group. That's when I discovered the 2N4401-4403 pair, that were very low noise compared to most bipolars, and designed my first jfet input tape recorder reproduce stage. I learned tape recorder design well enough to actually build my own analog tape recorder electronics a decade later. I also heard and came to understand digital audio, as we had a 50KHz 12 bit digital prototype and I got to listen to it. Those were the days!
Since 1972 it has been no problem. The first, I think, (even patented) disclosure on cross-quad and output stage layout to completely eliminate thermal offset from load current. Get up to date, it was more than 40yr ago.
A monolithic thin-film operational amplifier employing fully-protected super-beta transistors will be discussed. Drifts are less than 1 uV/° C, with source impedances as high as 100 kΩ.
Published in:
Solid-State Circuits Conference. Digest of Technical Papers. 1972 IEEE International (Volume:XV )
It's the stereo version, merely rewired to BTL operation.
The 2-channel SPA-4 model => www.hifi.nl/gfx/harberth_sugden_271106_3903.jpg
The designer apparently did not consider that running a bridged amp from 2 separate power supplies implies forfeiting part of the advantages of balanced class A operation.
(afaig, they're biased to a quiescent current level of 1.25A PURE class A. MasterClass, HUA ! © Al Pacino)
Part of the "problem" of defining this is that in a measurement sense the change may be from, say, 98 to 100. However, subjectively, the progression is more like 50 to 100 - there is a, hah!!, quantum change in the perceived quality, a transition or tipping point, when the mind no longer has to "work" at following the music threads - it becomes a subconscious thing to focus on the sound, the music just 'flows'.
Personally, I would use 100 to represent this crossover point, and all systems are in a negative territory with respect to this level - the question is, are they 20 "points" down, or 10 or 2, and so on ...
The point in saying this over and over is what? If your competition is just this mediocrity you could run at idle.
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