power conditioner

Well, I have done blind testing.

Test conditions: wall (dedicated audio line with 12 AWG) with factory power cord, wall plus $2000 power cord, Plitron isolation transformer with factory cord, Plitron with $2000 cord.

The last two conditions were clearly better, and indistinguishable. So I spent money on isolation transformers.

Further, an isolation transformer also removes DC from the power line, which can really save your bacon (and your amplifiers) in a storm. So, if you have expensive gear, an isolation transformer is just reasonable care and insurance.

But they do tend to growl when working, so they should have a place outside the music room.

Would like to directly answer the question posed at the start of the thread. My opinion is yes, power conditioning is important and no, it does not - or more accurately should not - improve the sound quality.

As I’ve stated elsewhere on this forum power conditioning is more appropriate for piece of mind and general health of the components in that they can be surge protected, under/over voltage protected, regulated (more expensive), etc. If sound is noticeably effected then there is something wrong other than power supply. Any change of sound should be subtle at best.

My system is dead quiet when "idle". I’m using a relatively low cost ($350) approach of dedicated (separate breaker) 20 Amp outlet >>> Emotiva CMX-2 (D/C filter + RFI/EFI/Noise reduction) >>> Panamax MR-4300 (same manufacturer as Furman 95% as good 65% of cost) for RFI/EFI/Noise/Surge/Over/Under protection >>> my entire A/V system.

I guess the way I look at it is, I've spent all this money on decent components and while I have replacement value home owners insurance in the event of a lightning strike, we all know how that works out. A balanced power conditioner is going to supply your components with clean AC power eliminating noise, in addition (if so equipped) it will protect your system from electrical surges. I guess those two things are in my mind worth the cost of the equipment. And it's not like they wear out so your investment can last for many many years.

Balanced power really helps my system.

Farzad, many people complained that dynamics were reduced.  In typical linear supply current is drawned in spikes of very high amplitude.  Any filter element will cause a voltage drop, hence reduced dynamics.  My conditioner Furman Elite PFI 20 has, in addition to filtering choke, a big capacitor able to supply high momentary currents.  Not only that bass is sounding more even (more melodic) - I'm not sure why, but TV plugged into Furman has brighter and purer colors (reduction of jitter?).  In addition my Furman has very tight non-sacrificial over/under voltage protection.  Since the day I bought it we had few cases when bulbs suddenly got unusually bright and Furman switched OFF to switch ON automatically again when condition passed.  I would never connect my gear directly to wall outlet.