Help, is it clipping? or cables? or...feedback.

Here is my problem....on loud transients the treble moves forward and becomes harsh. If I add negative feedback on amp, this seems to help. But, negative feedback sounds closed in. So, what is "choking system?

AMP is VAC 70/70 driving Diapason adamantes II. Cable Mapleshade double golden helix. Is it the cable? Amp / speaker match? Or, is it upstream...theta data II, VAC DAC tube DAC? preamp does not seem to be issue as I have tested several.

Or, is this just plain digital? I am using what I consider to be best recordings....

Any thoughts? I am considering a cable redo...I have a mish mash of them in system.

Thanks!