I agree with Jdombrow as I'm a big fan of AC line conditioning, dedicated circuits/lines, cryo-treated lines, etc., but proper AC line conditioning and tweaking has everything to do with the lowered noise floor, pristine sonics, enhanced soundstaging and imaging, minimizing / eliminating negative sibilance, etc..
It sounds like what you are experiencing has everything to do with equipment that is incapable of faithfully reproducing the rise and fall of a musical note in or near it's entirety. Some of the MacIntosh gear is notorious for this.
The common buzz for this is 'fast'. For example, you want a 'fast' amp that has the ability to meet the fast rise and fall times of a given note that also illuminates the intertransient silence between the notes.
Very few amps can properly meet this demand for speed and there are certainly some that fall way short.
The result is that the dynamic punch is gone, no PR&T, no excitement, one note leads right into the next, and you almost feel that the tempo of the music has slowed in comparison to another system.
I would suggest demo'ing a few different amplifiers to start and doing a search on Agon for fast amps.
The problem is not limited to amplifiers only, but that's as good a place as any to start.