I bought the APC H10 so I could plug all power cords into it and eliminate the mess behind the AV stand. It works as advertised and I have only one minimal criticism of it - there doesn't seem to be much difference between the 8 levels of dim and the lowest setting is still somewhat brighter than I would like.
I wouldn't say it does anything to 'improve' the audio or video but for me it is convenient to plug everything into and every once in awhile the boost or cut light will illuminate, indicating that it has corrected an over or undervoltage situation.