Downsizing from Audio Research REF110 to 100.2

If you are open to other brands, I would recommend you consider the Pass XA.5 series or Ayre. They have been my favourite SS amps, but I'm not saying they are better than the ARC you are considering as I have never heard it. I think that the reason I like so much is that they use very little feedback and as a tube lover, I think this approach to SS makes for better sounding amps to those that like what tubes can do.

Jglpubli, first, let's take it a bit further.
Few more questions:
1) is the REF3 broken in? Do you at least have 500 hours of playing time on the unit?
2) REF110 - how many hours? Broken in or not? Should have at least 500 hours and even more to be considered for a serious audition, same as REF3.
3) Have you had the D200 on these speakers or you had other speakers at the time?

If it was with these Proacs, it is pretty much a hint that you may just need more power to balance these speakers out. that's one. Also, D200 does not have the resolution of REF110. You are hearing a lot more imperfection now with the REF110 and REF3(don't know what preamp you used with D200). I'm just going by the fact you used a phrase "some recordings". So that should be considered as well. Let's not forget the high resolution of the ARC REF stuff.

There are few variables. Best is trial and erro as far as equipment for a specific speaker, be it a ProAc, Wilson, B&W or what have you.

If at all possible, borrow a more powerful solid state amplifier to try with your REF3. Try to audition a nice solid state, hybrid(tube/solid state design such as ARC's own HD220 or Moscode) or a more powerful tube amplifier.

You can have the best possible pieces in your audio rack. But if they don't synergize, whatever you have isn't a "system". Yes, good on their own, but not necessarily together.

Also, I very much doubt 100.2 will satisfy you. it is a very good amplifier, but I kind of doubt it will drive the Proacs any better than the REF110 do, especially if the reason for your complaints is due to lack of power. The only thing you may gain with the 100.2 is somewhat more forgiving sound overall, because it won't have the resolution of the REF110. But it will be still lacking.

Try to audition few different amplifiers, possibly more powerful than the REF110. Some to consider would be Classe, Pass, McIntosh, McCormack DNA-500, ARC HD220.

May be I'm wrong(wouldn't be the first time), but it seems to me it is a matter of finding a proper amplification for the speakers. Also, work on the room acoustics if situation allows. Very essential.

I strongly agree. Keep the REF110.

I don't want to push Pass to hard to someone who owns and likes ARC which is very fine equipment indeed, and the REF110 has a very good reputation, BUT, if you do want to try SS, I have to agree with Tvad, that the Pass XA.5 series is fantastically good and worth an audition. I had an XA30.5 with my Merlins (they don't need too much power and the Pass seems to be very conservatively rated) and it gave my CAT JL2s and Music Reference RM9SEs a run for their money; I regret selling it, it is darn good and an amp a tube lover can appreciate. There is a dealer in Iowa that carries both ARC and Pass and they may be able to give you some insight into pairing the REF3 with a PASS amp. I would expect it to be a wonderful combination given the neutrality of the ARC with its tube bloom with the quiet, transparent, and warm side of neutral sound of the PASS - worth considering - and very reliable and fuss free.