I have a Yamaha DSP-AX750SE amplifier and Castle Compact 5.1 speaker system. I am rather dissappointed with the stereo sound and thought it was down to the speakers (because my old Morduant Short speakers sound ok with the amp). However a bloke in an up-market hifi shop tody suggested that it is because my 'speakers are showing the amp up' (and the Morduant Shorts are a bit knider to it, and better balanced) and I should be looking at the something like the Arcam Diva for £1, 300. Anway, he did recommend that in the meantime I switch the impedance setting on my Yamaha amp. I had it set on 4 ohm minimum, even though all the Castle satellites are 8 ohm, because the Castle Centre is only 6 ohm. The bloke told me to switch the amp to 8 ohm anyway, saying I was unlikely to hurt the centre and in fact was more likely to hurt the sattellites with the amp switched on 4 ohm. I have tried this and, unless it is my imagination, it does seemed to have opened up the sound a bit. But do you think I am likely to hurt my 6 ohm centre speaker, or any of the others, by doing this? And is the apparent improvement more likley to be my imagination? Thanks.