are all power conditioners noisy?

I use a Panamax Max 5500 ACRegenerator that uses a large transformer to decouple wall AC from AC provided to equipment... my ear has to be practically right up to the unit to hear any noise at all... and even then it's extremely low in volume.

24phun, sorry you had bad luck regarding your power conditioner. I use for my digital front end the Ensemble Duo Isolink and for the rest of my system Richard Grays Power Station, two of them in what's called a star cluster arrangement, with great results.

Total dead silence with the background noise floor gone with air around the players, more precise layering in the soundstage, more natural timbres, without any loss of dynamics or prat.

There are many power conditioners on the market, I auditioned about five different ones before finding what I wanted, so I would suggest you try to audition some new pieces to find what you are looking for.

My experience has been that all power conditioners (that I've used) are dead quiet.

I have an API Power Wedge 116 - hums.
I complained to the mfr and they replced two of the three isolation transformers. It helped tremendously but guess what? It still hums - just not as bad.
I also have the Monster HTS 5100 - hums too.
If it has a transformer it is susceptible to humming!
Variations in the inpregnation of the windings will allow this to happen. Mfrs. pull a vacuum during impregnation but, to cut corners, they don't pull a vacuum as long as is really necessary to get all the air out and so occassionally, you'll get humming. Grrrrr!
At one time I owned two Parasound A51 power amps at one time - one hummed noticeably, the other did not - go figure.

I would follow the other suggestions of trying to damp the transformer/housing and tightening screws. At least you will kill the hummming transferring to the housing which is probably the bulk of the annoyance.