For power, using cleaner power will help improve sound quality, particularly the sound stage. We are using ASR Active Cable to feed power to DAC2, notebook and line driver. It is a good upgrade.
I'm also using some old power cord I have, recommended by one of my customers. Brand name Camelot Technology from US/Japan. Work well so far. But it is hard to find in 2nd hand market.
I have just online ordered a new power cord with very good feedback in forums. Will share whether it would further improve the sound quality.