Hi Joe, I think I have told you previously that I used to run a Cary 805AE SET with a pair of ProAc D38's. Absolutely right, they sound shrill! It took a long time before the sound settled, but the frequency balance was always tipped towards the upper registers. After a lot of listening, I think that the reason they sound shrill is because they are clipping when the volume is turned up. It doesn't take much to clip these amps, given how low powered and intolerant of impedance swings they are.
I tried to tune out the harshness by swapping tubes but I did not hear any difference. In retrospect, I think that the constant clipping was masking any difference between the tubes.
With some types of music - female vocals, violin solos, small string ensembles - and played at a low volume - they are amazing. Incredibly transparent, lush, and magical. BUT if you throw something big at them - e.g. orchestral works by Shostakovich and Mahler, they really struggle. You can hear the clipping by listening for dynamic compression. Orchestral surges don't get any louder. And you get a lot of high frequency hash.
Given that you have the Cary's and the AR - why not try bi-amping your speakers? Does your preamp have two outputs? Otherwise, try a Behringer CX2310 crossover. I know, I know ... it is a $150 analog crossover. But it is cheap enough to buy and try. In fact, I have a spare one here which I can send to you for free for evaluation if you pay the shipping
