I, too, had a similar experience with my Aries Cerat Helene DAC, but it was not the PC; it was the interconnect (Nordost Valhalla 2 XLR). I do, however, power the AC with an Audioquest Hurricane PC. The addition of the Valhalla 2s between my source and McIntosh C2700/MC611s was immediately apparent with the highs. McIntosh is known to be a little restricted on top, but no longer with the Valhallas. I was skeptical that the source cabling could profoundly affect the system. I always thought the preamp/amp connection would make the most difference. Boy, was I wrong!!
Moved Audio Quest cable to my DAC. WOW
I just moved my Audio Quest power cable to my DAC and noticed a more realistic open and better detail.
I have always been skeptical due to my electrical engineering bbackground.my wife also noticed a better sound.
The cable never really made any difference on my JC5 amplifier but maybe as someone else pointed out, power cords make a bigger difference on up front equipment with less sophisticated power supplies.
Ordered a linear power supply conversion for my streamer. Will see what that does.