Rleff:
I did, yes. Assuming your question goes to the differences between battery power and wall power, I had 20 amp dedicated lines and battery power was still the way to go. The batteries, even in a highly resolving system, brought no improvement at normal listening levels. It was only during very demanding orchestral passages that the batteries showed their worth - because they provide a very low-noise power supply, the crap/grunge that would normally find its way into the signal path, and which gets amplified very audibly at high volume, is largely absent. The effect is a sense of more natural dynamic range, even though the batteries actually lower available peak wattage. The benefit is also audible with cleanly recorded rock played back at high volume, but mostly, the batteries are for people who are very serious about the playback of orchestral music.
The Rowland Model 2 and 6, if run from batteries and run balanced (i.e., with fully differential balanced source components and preamp) in a well-assembled system, offer some of the very best performance available from solid-state. I sold my Model 6's several years ago (my current amps are a darTZeel solid-state amp and VAC Renaissance 70/70 Mk. III triode tube amp), but have been running a Rowland Coherence II battery-powered preamp in my main system for seven years now.