Audio Research D240 mkll vs Adcom GFA-555

I happen to think the ARC is just fine myself, having owned and happily used 2 different SS ARC amps in the past.

I was not specifically promoting the Adcom amps, re mods or whatnot, I was just covering the fact that not all amps are as they could be, or can be, due to the constraints of reality.

If I was to start with an unknown base amplifier, and then modify from there (all being equal), I would start with the ARC amp, not the Adcom.

But I would happily tinker with either brand of amplifier.

It is possible to make one sound better than the other and then keep working on each... and make each leapfrog the other in sound quality. Back and forth, back and forth...

As this is the main thing about most all amplifiers. Having seen the insides of almost any amp known to exist in the high end (nudie amplifier images abound all across the net), I will say that I have not yet seen an amplifier that could not benefit from a little intelligently applied TLC,  be it a $2k amp or a $100k one.

Point being, is that it is really..near impossible to say that one has a modded out Adcom, vs an ARC that is stock, and then get an opinion.

As the modification level or what was done to the Adcom, is an unknown except to that of the owner, but that the ARC is a known quality for at least some, as it is a known model with a known stock condition and sound quality. That the modded Adcom is an X that no one here outside of the owner of it can quantity and weigh against.

It is a good question, but it is lopsided for all but the OP... and we cannot help solve it.

I bought an Adcom 555 MKII, along with a GFP-565 preamp, brand new back in the 1980s and used them with Magnepans for about 5 years. I never had it modified and what teo_audio stated in his post about graininess makes a lot of sense to me. I subsequently used McCormack and Aragon high current amps over the next 10 years and, in my opinion, they both sounded very similar to each other and both were significant upgrades over the unmodified Adcom.
Over the past 5+ years I’ve used class D amps, stereo Class D Audio and Emerald Physics units and currently a pair of D-Sonic monoblock amps. All of these newer class D amps outperform all of the large, heavy class AB amps I’ve previously used by a wide margin.  They're better in every area I care about: low distortion, high power, high signal to noise ratio, powerful and realistic dynamics, solid and stable imaging, highly detailed and possessing an overall accuracy, smoothness and naturalness. 
If you’re looking for a significant upgrade, I’d suggest trying out at least one high quality class D amp.


Tim

noble100"All of these newer class D amps outperform all of the large, heavy class AB amps I’ve previously used"

You must have employed the use of some really mid-fi or mass market class AB amplifiers in your Music Reproduction System if that was the result and consequence you experienced when substituting Class D amplifiers for them in you're system but the important thing is that you made some real, genuine, audible improvements and I can only suggest, recommend, and encourage you to audition some superior amplifiers within the same Music Reproduction System such as properly designed, specified, manufactured and installed Class A amplifiers. Good luck to you there is more out there don't stop now!

clearthink:" You must have employed the use of some really mid-fi or mass market class AB amplifiers in your Music Reproduction System if that was the result and consequence you experienced when substituting Class D amplifiers for them in you're system..."

Hello clearthink,

     As I stated, I've used 3 high current class AB amps in my system thus far, an Adcom, McCormack and an Aragon.  I believe most members would consider all 3 of theses as at least good quality class AB amps with the possible exception of the unmodified Adcom being considered mid-fi and mass market. 
     I think a very large and expensive Pass Labs AB amp would be required for a class AB amp to outperform my current D-Sonic monoblocks.  I've auditioned Parasound and Bryston high current amps already and discovered those will not.
     Sure, an even larger, hotter and much more expensive class A amp may sound marginally better.  But my D-Sonic monos are smaller, run cooler, were $2,100/pair, are paid for, consume orders of magnitude less electricity to operate and I perceive their sound quality performance  as exceptionally good.
     Thank you but I don't consider your suggestion of switching to class A amplification as clearly thought through. 
     However, I suggest you consider auditioning a good quality class D amp in your system to broaden your audio knowledge and experience.

Tim

noble100" I've used 3 high current class AB amps in my system thus far, an Adcom, McCormack and an Aragon. I believe most members would consider all 3 of theses as at least good quality class AB amps with the possible exception of the unmodified Adcom being considered mid-fi and mass market."

Those are not only mass market midfi amplifiers they are so old as to be nearly laughable they would likely need substantial service and parts replacements because of the age of the components contained there in.