I have used iFi's DC Blocker in the past; however, it was not the "+" version, so I kind of knew what to expect. I use the non "+" version with my CD player. I wanted the "+" version to use with my amplifier as it appears to be able handle more power/current. As predicted, the transformer hum was reduced a little but not eliminated; however, it removed a layer of harshness from the music, tightened up the bass a little and increased bass impact - I had to turn down my Rel sub a few clicks. The main effect is a relaxing, more calm feel to the music with a blacker background - you don't realise there is noise present until it is removed. Please note, the difference is subtle and certainly not night and day; however, for the discerning audiophile, it will likely be £150 well spent.