As an Audio Research fan (after many years of listening to other manufacturers), I can assure you that the Ref 150 was a huge step up in bottom end and solidity to images from the Ref110--say 20 to 25 percent. The Ref 150SE is another, albeit smaller step up from the Ref 150 (although you can put KT150s in the Ref 150 and be extremely close to the sound of the 150SE)--say 10 to 12 percent. The Ref 160Ms are yet another step up from the Ref150SE but IMHO not quite as big as the step between the Ref 110 and Ref 150---say 15 to 20 percent.
Of course, these are all of my opinions in my system in my room.
I also like VTL, Lamm, Aesthetix, Doshi and BAT and for solid state, Soulution, Wells Audio, D'agostino, T&A and others, but each manufacturer has its own house sound and improvements over the years or in the product line from low to high come not as modifications to the sound--so much as shoring up weaknesses in the house sound. With ARC, the only major weakness of the Ref 110 to my ears was its etherial presentation that sometimes presented images as too wispy. As a result, it also did not have an impactful low end. The Ref 150 cured that problem and since then, ARC amps to me have been extremely well rounded and a pleasure to own.
Of course, these are all of my opinions in my system in my room.
I also like VTL, Lamm, Aesthetix, Doshi and BAT and for solid state, Soulution, Wells Audio, D'agostino, T&A and others, but each manufacturer has its own house sound and improvements over the years or in the product line from low to high come not as modifications to the sound--so much as shoring up weaknesses in the house sound. With ARC, the only major weakness of the Ref 110 to my ears was its etherial presentation that sometimes presented images as too wispy. As a result, it also did not have an impactful low end. The Ref 150 cured that problem and since then, ARC amps to me have been extremely well rounded and a pleasure to own.