I wouldn't "downsize" at all. The REF 110 is a great amp, but if you want to go the SS route, what I would do is sell the REF-110 and buy a HD-220. Tons of power, great base and still the resolution and musicality of tubes that we all like ... and its a good match for your REF-3.
Downsizing from Audio Research REF110 to 100.2
I have an Audio Research REF3 and REF110, I pair them with Proac D38 and Transparent ultra MM biwire speaker cable.
I want to keep the REF3 but I am going to try the very well reviewed solid state Audio Research 100.2, I like the REF110 but I want to have more simplicity in my system and not to think about if my power amp in switched on or not.
I also wanted to convince myself that I am not such exigent to need always the best, I had in the pass an Audio Research D200 which left to me good reminders, I know that 100.2 in noticeable better so I think it could be enough satisfactory in my system.
Someone having some experience with both amplifiers?
How they would compare?