Tenson,

I must be missing something here.

You don't bi-amp Kensai's because :"The Kensai work very well on the end of my 50watt RMS Cyrus 3. But that amp has a big PSU and will probably kick out as much as 300watts for short bursts"

How is it when it comes to my 70 watt monos : "When an amp distorts with HD, IMD or clips (which 70watts will do with dynamic material in an 83dB speaker) the distortion created is high frequencies that go right to the tweeter." , But when it comes to your 50 watt Cyrus it can produce 300 watts on demand?

A fifty watt amp is fifty watts, unless we start down the argos catalogue route of describing output in ridiculous RMS pseudo-figures like they do on their glorified karaoke machines. By those measures the large psu in my larger amps can produce something near 600 watts during peaks in the music. So if that is the case why would I hear any improvement through bi-amping? They are still seventy watt monos and it is daft, even misleading to say otherwise, even if it is just for a microsecond at a time.

I don't think clipping is the issue at all, even with an 83dB load  - certainly I heard no clipping at all. How can an amp - yours or anyone's -  produce signal larger than its own voltage rail without clipping anyway?  Clipping therefore can't be an issue when it comes to bi-amping so why the improvement?

The thing is: Changing from 40 watt monos to 70 watt monos was great, as you would expect. But moving to Bi-amping with the whole set was just light years ahead - huge difference. That's not because I now have a thousand argos-watts on tap, it is because the channels are separate and the treble/bass is separated, etc.

There is more to passive Bi-amping than meets the eye, certainly a lot more than clipping. In fact, even the benefits already mentioned don't quite go all the way to explaining the improvements on hand. Bi-amping somehow (if done correctly) is greater than the sum of it's parts.