In my main system, the Blue Heron II's moved out my Wilson WP 7's. I tried a Musical Fidelity Trivista 300 integrated, Audio Research VT 100 Mk III, a McCormack DNA 1 modded Platinum, but finally settled on a pair of BEL 1001 Mk V switched to mono.
The BH's are 91db efficient, so lower level tubes or smaller integrated (Lavardin?) have worked well for others. I am more than happy with my system as it is (using a tube pre, Hovland HP 100, Sword and Audience AU cabling), and despite several trips to RMAF and lurking around some larger HiFi stores, have not had the urge to change speakers. In medium size, treated room, these guys show their stuff, and I listen for hours without fatigue.
Moving into computer audio; wonder where that will take me; but rest assured the BH's will go along for the ride.