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.