In search of more power ... MF? V Alstine?

I like the sound of my Opera Consonance a120 Hybrid Integrated amp (90 w), but my 87 dB speakers and large room size dictate a need for more power. Somewhere around 200-250 wpc perhaps. I was considering staying with an integrated so I could help fund my new purchase with money from selling my current one. I auditioned the Krell KAV 400xi - it was powerful and dynamic with kick-ass base like I've not heard before (too much?). BUT, not lush enough in the mid-range for me. So next up is a Musical Fidelity A5. I will audition this in a couple of days. BUT, Van Alstine Fet Valve Ultra 550 keeps creeping into my pea-sized brain. I've never heard any of his stuff, but I can't shake this nagging suspicion that it may be just what I'm looking for. However, I live in Atlanta, not in the frozen tundra a.k.a. Minnesota, so an audition seems impossible. How does the quality (sound/build) and mid-range compare between the Musical Fidelity and Van Alstine Fet Valve? And what about using my a120 pre-outs to provide the source for the 550? Or can I buy a better pre-amp than the a120 for $600 (the amount I'd likely get if I sold the a120)?