Harmonic Recovery "Boxes"

I agree with what Otis said above. I have a single-end HRS which I installed between my BAT VK-5i and Aleph 3. I thought it made my tube preamp sound solid state. The highs had perhaps a bit more detail, but there was an edge to them that I didn't like. I read the reviews that reported an increase in soundstage depth, but I didn't experience that in my system. It does increase the gain by about 10 dB. I haven't tried it with a solid-state preamp yet, and maybe the BAT just wasn't a good matchup for the HRS. A friend of mine has the same unit and tried removing his preamp from the loop and just using the HRS between his CD player and amp. He also tried it with his B&K pre/pro in the loop. He reported good results both ways. I also agree with Gmkane. I think the better the system, the less an HRS is going to help, if at all. If you have a modest system, I can see how an HRS might be right for you. $200 or so for a used one is certainly a lot cheaper than a quality preamp. Also, the HRS would probably work well with a passive preamp, as the increase in gain alone would be welcome.

I have the Audio Harmony which replaced the HRS. There is an upgrade to the HRS that not too many people know about.

I have owned an HRS for about 18 months. The most significant improvement in my system (Wadia 850 CD player, Linn Klout power amp, Magnaplanar 3.6R speakers) is that images are more precise and have more of a correct "size". With the HRS, female vocalists are more "right there in the room", and the voice comes from a correctly sized mouth. Without the HRS, the vocalist is more "smeared" (more diffuse) and the sound of the voice seems to come from too large a part of the soundstage. I believe the HRS helps my cd player drive my amplifier better, just as the advertising says. Would the HRS significantly help a state of the art preamp drive a state of the art amplifier better and result in more musical sound? I don't know, but I know I like what the HRS does in my humble system, and it is always in the system. I really like the sound of music my system reproduces using the HRS, and I am glad I bought it. I purchased a premium power cord with the HRS. Recommended. Best of Luck.