Best ARC Solid State power to match ARC Ref 5 Pre

Audio Research makes some of the best solid state amplifiers out there. Unfortunately their solid state amplifiers do not receive the credit they deserve because Audio Research is primarily known for their tube electronics. That said , I can highly recommend an Audio Research D400 MKII. The D400 MKII will mate perfectly with your Reference 5 preamp and it will have plenty of grunt for your Sophias. The later version would be the D225 or the Reference 150 depending on your budget. I used a D400 MKII with my ESP Concert Grands and I can tell you from experience it is a terrific amplifier. I would put it in the same league as Levinson, Krell and Threshold and much better than the others mentioned here.

It would be nice if folks here could recommend something other than what they are currently using in their system.

Raquel, That's your opinion and I also disagree. I have owned many amplifiers over the years and Audio Research amplifiers are one of my favorites. I have owned all types including all tube, hybrid and solid state and Audio Research never fails to impress.

Just what we need. Another $18,000 solid state amplifier that's supposed to sound like a tube amp.

Bifwynne, I agree there are many other brands of amplifiers that are very good. I currently own amplifiers from several different manufacturers, but the OP specifically asked for recommendations from Audio Research. I also agree with you regarding system synergy, but there is more to it than just matching speakers and amplifiers. I believe matching preamp and amplifier is just as important and Audio Research is one of those brands that seems to work best together.