Lcherepkai, switch mode amps like Rowlands, Belcanto, and probably W4S seem to take an inordinate amount of time to break in. I'd make sure they have about 1200 hours of playing time before doing critical listening. One more interesting thing about ICEpower amps, is that they like to be left powered up between listening sessions to sound their best. If you turn off switch mode amps for a few hours, it might take them more than a day to revert back to top performance. Good news is that they tend to draw extremely little power when idling. Your W4S probably draw 9 to 10W each on idle. I turn off my Rowland 312 only when a thunderstorm is approaching, or I have to leave home for trip. G.