Starting a thread to share and talk about power conditioning. I've set out a bit of what I've tried and the results.
1. Outlets with built in surge suppression and filtering
These range from the cheap and cheerful computer variety type of outlets (like Belkin, APC etc), to the dedicated audio brands like Tacima or China brands like Bada, Longyu and Weiduka. Although the parts count varied, you would expect to find a MOV for surge suppression, a couple of capacitors and a choke(s) for filtering.
I personally didn't have much long term success with these from a sonic point of view. For models that use universal outlets (you know, the type that can accept both a UK or US type plug), I always had a problem with intermittent contact.
2. Parallel filters
The really popular products of the past were the Audioprism Quietline and the PS Audio Noise Harvester. The main advantage of these products is that they were connected in parallel to the mains, and did not limit current. Many products in category 1 incorporate parallel filters. These operate at radio frequencies and above. As they are quite small, you can use a few, close to the source of interference where they are most effective.
I actually find these quite useful. I made my own, and the parts used have a profound outcome on sonics. Sadly, the best sounding capacitors are not rated for continuous mains use. That being said, you could get decent results using properly rated parts.
3. Regenerators
Made popular by brands like PS Audio and Pure Power. You have the rectified DC, and an inverter to regenerate the 50 Hz (in Singapore) sine wave. The Pure Power threw in a rechargeable battery.
I personally use the CSE RG-100. Regenerators tend to be big, heavy and not particularly efficient. My CSE runs at 50 % efficiency and generates a bit of heat too. They can sound really good, but I dislike the fact that you can't leave your equipment permanently switched on (at least without a shocking electricity bill and shortened regenerator lifespan)
4. Isolation transformers
Like balanced transformers, the type of transformer used has a big effect on the sound. Concept is quite simple. Have your mains line magnetically coupled via a 1:1 transformer. The 50 Hz AC gets across, while all the rest of the nasties don't (at least in theory). Your are limited in current based on transformer size. Transformers large enough to power a large hifi system are big, heavy and bulky. If you are really unlucky, you may even end up with a physical buzz on your transformer.
5. Balanced transformers
The concept of balanced power is interesting. Split the incoming mains into two legs, e.g. 230 V gets converted into 115V+ and 115V-
Have a read here for more information,
http://www.equitech.com/articles/bpng.htmlNoise is cancelled via common mode rejection. Like isolation transformers, you are current limited by the size of your transformer. I currently use our locally made product, the Plixir BAC from Sound Affairs - quite good results.
