My system has all-digital sources (Roon server & disk transport) with a DAC that is separate from the preamp. I have found that conditioning the power improves the performance of my DACs, most notably tightening up the bass and improving the stereo image and soundstage. Each time I've improved my conditioner, the sound quality improvement is immediately better. I can't speak to whether power conditioners would improve a system with analog sources, but I'd say "yes" to those with digital sources.
