Need help determining next upgrade - 3rd ATTEMPT

Have you played around with speaker location, like maybe a few feet from rear wall or so? Possibly a tad closer together in conjunction as well. Speaker location relative to walls is a big factor usually for good separation and sound stage. With that, can also come less congestion and better detail.

Start with a good mono recording and get a solid and focused image between the speakers first. Then try some things in stereo. IF mono recordings are imaging clearly that is usually a good omen for stereo.

After that, you might try some sound absorbing panels or other sound absorbing materials or room items at first reflection points along the walls based on your primary listening position.

Then any other tweaks if still needed from there.

If digital, you can currently pick up a Pangea audio ac14 se or ac14 power cord for your DAC depending on the one currently in use, for well under $100. Using a power cord like this designed for digital source applications can probably only help and not hurt.

I am noticing improvements similar to what you seek since applying the ac14se with my mhdt Constantine DAC. I did the upgrade needing to replace an existing damaged power cord and knowing that I have greatly improved performance of my setup in the past by systematically shielding against EM noise.