I have a Superphon SP100 - it's a buffered passive preamp, so it does have a power cord. I traded a VERY good Yamaha integrated amp for it, and am currently using it between my Bluray player and my power amp. It is simply because the TV's internal speakers are going bad, and yeah, I want that BASS! My main system uses a tubed, one-input, one-output, no tine controls preamp, powered by eight "C" cells. It's very quiet. I like it better in some way than the passive.