Probably gives him more distortion, because impedance of the AC is important for hi-fi equipment, and power conditioners can make the impedance worse.
Only in cases, where the impedance of AC mains is ridiculously bad can an expensive power inverter improve the performance of normal (reasonable) hi-fi equipment:
This is a review and detailed measurements of the PS Audio PowerPlant 12 (P12) AC regenerator. It is on kind loan from a member and costs US $5,499. PS Audio nails the industrial design of the unit. I really like the casework as well as the look of the various graphical meters as you see above...
www.audiosciencereview.com
Audio interfaces and dedicated phono stages sometimes use an external 12 VDC adapter, because they don't need much current.