About tweaks i prefer homemade one (acoustical one and mechanical one ) but sometimes i reach my limit ...
I am not an electrical engineer...
My best tweak after Schumann generator well located in the system and grid of Helmholtz resonators well located (low cost)
is a Chinese set of buffer and filters for your low cost dac and pre-amplification they gave the needed clean power at the right time...( i recommend linear power supply especially sone low cost one from China )
I owned 3...
If your system is low cost you must try them....( i say that because i never try a 30 bucks buffer with a 4,000 bucks dac , mine cost under 200 US bucks )
Lusya technology aliexpress ...
They cost me under 100 US bucks, not for one but for the three of them , with no Tariff, and postal cost included ...
They are stupendous for the cost ...