This is like groundhog day for me. After going a week running my DAC directly into my amplifiers using relatively short 1M interconnect cables, I continued rearranging my system layout and reintroduced my buffer/preamp between the DAC and my amps and.....Shazam! Technicolor! Better soundstage depth, better body, deeper tone, more impactful and deeper bass, and a more realistic and less electronic presentation.
It seems this happens every time I try to go without my preamp/buffer. Maybe it is my SMc monos, which have input impedance of only 10K ohms, but it was also like this with my former Clayton amplifiers (but maybe not as profound an improvement), which had input impedance of 100K ohms.
The other thing I did was replace my well-regarded Oyaide power cords with 7 awg NOS Western Electric cords and wow, an immediately noticeable kick in the pants. The amps are 650 wpc and are each run from their own 20A dedicated circuit. Going from 10 awg to 7 awg made a substantial sonic improvement. I don't typically notice huge improvements from cables and tweaks but this one was substantial.