Bombaywalla, Bifwynne - No, I don't know the numbers, but suspect it is at about a half or less. Delivering full power at high frequencies is not really important since very little power goes to tweeter. In my Rowland 102 max power at high frequencies would damage amplifier (burn out output choke). Icepower module 200ASC used in my amp is specified at 200W at 10Hz-20kHz but it is only momentary power. FTC rated power is specified as 55W but only up to 8kHz, with warning about damage to the choke at higher frequencies. It is not really important because average power when playing music is only few percent of peak power. The reason for that is that if on average music has half of peak loudness, it means 1/10 of power (logarithmic scale) and then music also has gaps (unless one listens to sinewaves). 55W of power at any frequency above 8kHz would most likely damage any tweeter, not to mention hearing. What worries me a little is 22 deg phase shift at 20kHz (-3dB bandwidth is 65kHz). It would weaken upper harmonics summing. My amp would benefit from a little more "air" but it might also be my hearing (not getting any younger) or the fact that speaker has warm character and is never bright - even on worst CDs. It has, in the system, very clean, pronounced natural sibilants. I don't want to change it and before I audition another amp (like Rowland 625) I need to fix room acoustics.
I understand Rowland's idea behind 350kHz bandwidth in model 625 - no phase shift at 20kHz and perfect step response but 1MHz bandwidth of Soulution 710 is perhaps too much. According to reviews it is excellent amplifier with very little negative feedback but in general the easiest method to improve most of amplifier's spects (like THD, IMD, DF, Bandwidth) is to use deep negative feedback that also enhances odd harmonics (overshoot in time domain caused by amps signal delay and thus late feedback summing - known as TIM) making unpleasant bright sound that SS amps are famous for. Class D has small advantage here, being practically one stage (little delay). Less than perfect design of such 1MHz amp can cause problems including instability followed by oscillations that can damage speakers or sensitivity to RFI. I would tend to agree with Audiofreek32 that numbers are not that important and often amplifier with the best spects has the worst sound. Selecting gear for audition by company reputation or designer's name makes more sense to me.
