power conditioner with off switch

Well, many will do just that- including the BPT that I use. But I trust you don't mean just shut down everything by the Power Conditioner switch- I definitely would never recommend that. If you mean shut down each component in sequence THEN shut down the power conditioner, well yeah, that's much better.

I use tube amplification so having a power conditioner that (a) cuts the mains power completely and (b) offers sequenced on/off cycles is a must. I've had a simple, cheap Rotel RLC-900 (about $200) for years and though I'm sure there's better out there, I've never had a reason to upgrade. It does its job competently, reliably and without fuss. I've also never been able to hear any sonic downside to using it having compared the sound of various components when plugged into the Rotel and then directly into the AC socket.

Shunyata Hydra-4 and up have on/off switches