Choosing a mains conditioner is a very dangerous thing if your not careful. A mains conditioner, or maybe all, judging from the ones i tried in the 300 to 600£ category, can take dynamics or life out of the sound. For me using a mains conditioner lost the sparkle in my system, so they aren't up my alley. But i haven't tried BT nor several others so to completely wright them of would ignorant from me.
I did hear some good results though with a simple (but not very cheap) wireworld matrix power strip and mains cables that offer mild conditioning and really tightened up the sound, especially in the bass. It's not much gear for your money but improvement in sound is the thing were after aren't we?
But i have seen the light in isolation transformers, they isolate your equipment from mains noise caused by other devices. You can use one for the front end and one for the power amp(s). That, combined with good power cords made me a very happy man.