Audio Research D400 mkII

I've been running two ARC D400mkII amps in a vertically
biamped configuration for a number of years now with truly
wonderful results. It's a low global feedback design with
class-A biasing to approximately 25wpc. One awesome feature
is a separate tranny for the input stage. Dynamics (macro
and micro) are two strong suits of this amp.

Before the D400mkII I was running two ARC D240mkII SS amps
(120wpc/8ohm, 240wpc/4ohm). These two amps share very
similar circuit. The D200/D300 are slightly different
circuit and frankly a step below the D240/D400. The D130 is
more similar to the D200/D300 while the 100.2 circuit is
more similar to the D240/D400.

Although I have not had a 100.2 in my own system to do a
direct comparison, I have heard it enough in other systems
to feel pretty confident in saying that the 100.2 sounds
very similar to the D400mkII and vice-versa.

If you've got an opportunity to buy a used D400mkII in good
condition I'd say jump on it. You don't see many come up
here because they are such good amps. Around $2000 for an
8/10 D400mkII would seem fair. Anything less than $2000 and
it becomes a no-brainer. If you don't need 200wpc, then
definitely a 100.2.

ARC has quietly been making terrific SS amps for a long
time. They just get overshadowed by ARC's admittedly sexier
tube amps.

I have to agree here regarding the 100.2. I auditioned a lot of ss amps, including Krell, Bryston, Classe and thought the ARC much better for my tastes. Mixed with a nice tube or hybrid preamp (LS 15 in my case)you get a rich detailed sound thats hard to beat IMO.

Agree with all above.. ARC doesn't make a bad amp SS or tube. You will not go wrong here. I used a D200/SP9 pre and auditioned a 100.2 and was very impressed with it. Very similar, the 100.2 gets the nod for refinement, detail and bass punch, but otherwise close. I dont have experience with the D400Mk11 but those here that do I would trust the opinions. I ultimately went with VTM 120 monoblocks/S15 pre amp combo, as the 120's were a rare find, and found the SS amps were mighty close in sonics,especially timber. The tubes add the extra bloom in the upper mid and highs, but loss out in the tight bass dept.( to be expected)
I could easily live with the 100.2 and never look back. Hope it helps!