I thought I would take a moment to report certain of my experiences with Elgar Ultra Precision Line Conditioners
. In the last several months, I have purchased, fiddled with and listened to two versions of these conditioners inserted into my system, the 6006B and the 3006B. The former is approx 10A rated, the latter 30A. All UPLC models employ a substantial, double-shielded isolation transformer providing most of the AC electrical output, supplemented by buck/boost circuitry providing AC correction. Because the units do not regenerate the AC waveform, Elgar conditioners are very efficient, and they boast an impressive max 0.2% output THD. UPLC conditioners can be purchased on Ebay for a price typically in the range of $100-$200.
The build quality of these beasts is better than anything I've seen. Wiring is very thoughtfully laid out, using shielding for critical lines. Parts quality is very high and typically overspec'd using, among others, Dale resistors, film capacitors for the reference and power supply boards, paper in oil capacitors for certain functions.
A general weakness of these conditioners can be the state of their electrolytic capacitors due to age---units purchased on Ebay can be 10 to 25 years old and older. I have found that once these capacitors are replaced, the units, to my ear, healthily improve the overall sonics of my system, moreso than PS Audio units I have employed (which operate dangerously close to max specs---for instance, their amplifier board capacitors run 5% over max, and not even factoring ripple). I suspect that replacing critical resistors and capacitors on the reference boards in the units with Vishay and better spec caps would nicely improve their excellent functioning.
Note that Elgar UPLCs use fan cooling. The fan can probably be disengaged with little consequence under conditions of moderate loading.
Also note that Elgar posts service manuals
for their products, including schematics for the UPLC line, on their website.