Br56's experience matches mine. The L1290s may have tested at 90dB in-room at 1w input (there's about a 3dB boost from room reflections on average), but these sealed-box speakers can use all the power, current, and damping factor you can come up with. I had the L-1090s as I mentioned 11 mos. ago in this thread. Going from a 60/90 wpc (relatively) high current receiver to a true 55-lb. high current 200 wpc power amp was like, "Whoa! No way is this amp leaving the house!" It seemed to add 1/2 octave of bass extension, plus increased clarity, speed, and dynamics, plus a more liquid sounding presentation. It wasn't just powerful, it was simply better in every way--natural-sounding mids and highs like a tube amp while maintaining that SS-style tight grip on the bottom end.
Anyway, it doesn't surprise me that 500wpc would open such a speaker up even more.
Anyway, it doesn't surprise me that 500wpc would open such a speaker up even more.