Powerline Accessory Reviews

HiFi-Tuning Supreme Fuse, May 2012 (Vol.35 No.5):

This follow-up review owes its existence—at least in part—to a posting in a forum at www.stereophile.com. Commenting on Stephen Mejias's review of NAD's C 316BEE integrated amplifier in the July 2011 issue, forum contributor and Stereophile reader "dlb" wrote that the substitution of a HiFi-Tuning Supreme fuse and MIT jumpers had transformed his own NAD C375BEE from a great-value integrated into "the amp of his dreams." I had previously commented favorably on the original HiFi-Tuning fuses, in a sidebar to my review of Onkyo's A-9555 integrated amplifier in the September 2007 issue, and I knew that new versions of their fuses were now available, but I never got around to checking them out.

The posting by dlb provided an impetus for me to call Robert Stein of Ultra Systems, US distributor for HiFi-Tuning (they're based in Berlin), who promptly sent me a HiFi-Tuning Supreme fuse for the PrimaLuna ProLogue Premium integrated amplifier that I review in the next issue, and another for the CAT SL-1 Renaissance preamp, each the same amperage as the stock fuse (footnote 1).

As it turned out, when I looked in the box in which I keep miscellaneous stuff, I discovered that I already had a sample of the original HiFi-Tuning fuse of the correct amperage for the ProLogue. I tried that one first. It sounded better than the stock fuse, but not by much: a bit more clarity that allowed me to hear more details. However, when I then installed the HiFi-Tuning Supreme fuse (same amperage) in the ProLogue, the sound really did improve. Compared to the stock fuse, there was a marked increase in clarity that made me think of the old metaphor of veils removed. With the stock fuse reinstalled, the sound was generally fine; replaced by the HiFi-Tuning Supreme fuse, it was undoubtedly better.

Stein then called to suggest that I try the HiFi-Tuning fuse in both orientations. When I asked him if there was a "correct" orientation, he demurred: "Try it both ways—you'll know." I did, and indeed, the way I'd originally inserted it, with "250V" on the fuse aligned with "Use" on the fuse holder, produced a sound that was more lively, more dynamic. Why should fuse orientation make a difference? Search me . . . but it did. I could hear no difference when I changed the orientation of the stock fuse.

I then tried a HiFi-Tuning Supreme fuse with my CAT SL-1 Renaissance preamp. There was an improvement of the same sort that I'd noted with the ProLogue Premium, but it was smaller in magnitude. Still, I wouldn't say it was negligible—it's just that, at the CAT's level of performance, improvements are generally hard to come by. Reversing the fuse orientation had little effect.

The element of the HiFi-Tuning Supreme fuse is 99% silver impregnated with 1% gold. Its case is of ceramic rather than glass, for better resonance characteristics, and is cryogenically treated. The fuses are handmade and tested in Germany. The price is $59.95 per Small fuse, $89.95 per Large. That may seem like a lot for a mere fuse, but not when you consider the potential sonic improvement. I can't say whether replacing every component's stock fuse with a HiFi-Tuning Supreme will improve its sound, but it certainly had a beneficial effect on the PrimaLuna ProLogue Premium and the CAT SL-1 Renaissance. Recommended.—Robert Deutsch

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Footnote 1: The HiFi-Tuning Supreme Fuses cost $59.95 (Small) and $89.95 (Large), each in fast-blow and slow-blow versions. US distributor: Ultra Systems, 127 Union Square, New Hope, PA 18938. Tel: (800) 724-3305, (215) 862-6570. Fax: (215) 862-4871. Web: www.ultrasystem.com.