I have read so much about this, I have active DBL's - so lots of boxes and sometimes all those boxes buzz quite loudly! I keeping going back and forth about this and i guess the only thing I can really do is try one for myself.
Now the thing that worries me is if there is any loss of sound quality, especially in terms of PRaT or speed, because those things are the reason why I built an active DBL system in the first place.
I'm thinking of the big 10kVa Airlink model as they have been very helpful in answering my questions. I have a dedicated 40 amp circuit for the stereo and that was a large improvement when it was installed. Only thing is that it did nothing w.r.t removing mains hum. Now the hum is not audible when playing music at good levels, in fact it's only when watching the TV without the stereo that I find it especially annoying. Also, the system sounds better at some times of the day/night than other times so I was hoping that a BPS would at least make things more consistent. I want it to always sound good, as it should when you consider how much money was spent!
Any way, the only real reason I'm hesitant is because naim have always frowned on any thing in front of the mains to their hifi, but to be honest, I have not read any official stance against "balanced power supplies" from naim. You would have thought that they may have tried them at the factory with so many complaints about buzzing transformers.
If any of you with bigs systems that have had one of these installed are adamant about its absolute improvement or otherwise, I would really like to hear from you, especially if one has been installed in an active system which we all know is very revealing. I would especially like to hear if anyone was helped or advised by naim about installing one of these isolation transformers.
I'm in Australia, so we have 240 volt mains but I have read that using the BPS at 230 volts would help the naim gear as that was how they were designed to be used. Surely naims power supplies would benefit from not vibrating madly due to dirty mains, they probably would last longer too. I don't know any more, I've racked my brains on this, just don't want to waste money on a mistake.