I haven't listened to the BPT 3.5 Signature, though it was highly recommended to me. I had already tried the Richard Gray products and found that they transformed my system, both on audio and video - I had to recalibrate my video monitor as well. I have gone beyond a single RGPC 400 - I tried one first and was so impressed that I set-up my system's power around their products (SubSstation, RGPC 1200C and two 400 MkII's).
That is my experience though. I have a friend that can't hear any improvement on his system with two RGPC 600's. It's my opinion that power conditioners depend on the problems you have with power (if any), or with your equipment (not all equipment needs power conditioning). Therefore, you need to evaluate products in your system to see if they solve your particular problems, if any.
JMHO :o)
That is my experience though. I have a friend that can't hear any improvement on his system with two RGPC 600's. It's my opinion that power conditioners depend on the problems you have with power (if any), or with your equipment (not all equipment needs power conditioning). Therefore, you need to evaluate products in your system to see if they solve your particular problems, if any.
JMHO :o)