I did a bit of testing last night and this morning that lead me to believe that this is a great product and that bybees can benefit your system even if you already have good power cords and a power filter.
I have a Blue Circle balanced power supply, but wanted to see what Bybees could add... So, I borrowed a friend's Bolder Quantum power strip (with 2 Bybees), and plugged my Blue Circle into it. All of my components are plugged into the Blue Circle.
Well, at first I thought that the music lost a bit of energy. Then I remembered that cleaner power can sound like that due to the reduction of treble hash. I listened more last night and this morning, mostly to Sade and the Corrs (MTV unplugged album). I am hearing a lower noise floor overall. Soundstage is more 3D and realistic. Small details of vocals and instruments (e.g. harmonics, inflections) are also more apparent. There is a sense of purity to the vocals and instruments and I find it easier to understand lyrics! Plus bass is definitely tighter. In short, coherence and musicality took a definite step forward.
I've emailed Wayne re an order. The Bybee AC adaptor gives you the flexibility to use any power cord and still get the benefits of bybees in the power chain. In my case, by putting them upstream of my power filter, all of my components will benefit from bybee-cleaned power.