Certainly, the fuses inside your audio & video equipment are amongst the most underestimated components. These very cheap components have, in the first place, to carry all current that is drawn from the mains. Under most circumstances, much money was invested already in expensive to very expensive powercords. No further comments will be necessary to explain, that these crappy fuses will be a bottleneck in your system...
Relatively big enhancements can be achieved with little effort when replacing the stock fuses with fuses that are designed specifically for audio-/video systems.

Ordinary fuses consist of a glass tube, with on either end small steel caps with a layer of nickel over it. Neither of these parts are ideal: the ideal fuse for audiohas to start with a ceramic body, in whcih should be mounted a silver fuse wire. This wire is connected to end caps made from pure silver, that was covered with copper first, then gold plated.To top things off, all fuses are then demagnetized and cryogen treated for even better conductivity, and less distortion and noise.

For the HiFi-enthusiast, there's no denying of the fact, that a clean and constant power delivery can improve the performance of a HiFi system dramatically. However, the importance of audio grade fuses has always been neglected.

One would expect to have the biggest gain in performance with equipment, that draws heavy currents, for example a power amplifier. However, the results from our listening-sessions proved, that even equipment with small power consumption (for example a phono-preamp) exhibits a remarkable gain in performance.

Fuses always carry a high current that easily evokes metal fatigue. This causes a degradation of the conducting properties of the fuse-wire, thuis resulting in a degradation of the equipment in which this fuse was mounted. The HiFi Tuning fuses will have up to 90% less losses than prescribed by the IEC.

The HiFi-Tuning fuses are 24 carat gold plated. They are each handmade in Germany, precisely measured and tested, to give you the best from your equipment.

On one hand, many fuses contain a spiralised fuse wire, that causes a high resistance and inductance. On the other hand, we have the HiFi-Tuning fuses that contain a straight fuse wire made from pure silver. This results in a very low resistance and a negligible inductance.

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The HiFi-Tuning fuses are available in all usual current ratings, in fast-acting (F) or as a time-delay fuse (T). Two wide spread sizes are available, the European 5 X 20mm (3/4" X 1/5") and the American 6,3 X 32mm (1 1/4" X 1/4").
In the following table you can see all available ratings:

Ultimate² fast-acting, 5 X 20 mm: 125  mA, 200  mA, 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A, 1.25 A, 1.6 A, 1.8 A, 2 A, 2.5 A, 3 A, 3.15 A, 4 A, 5 A, 6.3 A, 8 A, 10 A, 12.5 A, 15 A, 20 A.
 

Ultimate² time-delayed, 5 X 20 mm: 50 mA, 80 mA, 100 mA, 125 mA, 160 mA, 200 mA, 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A,  1.25 A, 1.6 A, 1.8 A, 2 A, 2.5 A, 3 A, 3.15 A, 4 A, 5 A, 6.3 A, 7 A, 8 A, 10 A, 12.5 A, 15 A, 16 A, 20 A.

Ultimate² XT*, 5 X 20 mm: 1.6 A, 2 A, 2.5 A, 3.15 A, 6.3 A, 10 A.

US Gold² fast-acting, 6.35 X 32 mm: 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A, 1.25 A, 1.6 A, 2 A, 2.5 A, 3 A, 3.15 A, 4 A, 5 A, 6 A, 6.3 A, 7 A, 8 A, 10 A, 12 A, 12.5 A, 15 A, 16 A, 20 A.
 

US Gold² time-delayed, 6.35 X 32 mm: 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A, 1.25 A, 1.6 A, 2 A, 2.5 A, 3 A, 3.15 A, 4 A, 5 A, 6 A, 6.3 A, 7 A, 8 A, 10 A, 12 A, 12.5 A, 15 A, 16 A, 20 A.


* the extra slow blow (XT) fuse is a special one, needed for powerful toroidal transformers, unless an inrush current limiter is used. On your existing fuse the imprint "TT" may be present. These special HiFi-Tuning fuses can be recognised from their red printing (other HiFi-Tuning fuses have their printing in black). In case the right rating extra slow blow fuse (XT) is not available, we recommend the next higher rating "T" is used. Unfortunately, manufacturers not always state the fuse is of the extra slow blow type, in that case we have a "normal" slow blow fuse that has its parameters set according to the IEC 127 standard. These fuses are slower than normal slow fuses, however, the user cannot see the difference because the imprint is just "T".
To sum it up: in case you see a large toroidal transformer in your equipment, and you have a mains fuse with just the imprints "T", you'll have to order the next higher rating "T" fuse in case the right rating isn't available as an XT-fuse. This only applies to the mains fuse, not to all other fuses in your equipment.

After this upgrade, you will notice a tighter low-end, that seems to go deeper, more detail, and an alltogether cleaner, more natural sound that's reproduced with the right timbre.

The third generation "Silver star" (Ultimate³ and Gold³) fuses by HiFi-Tuning feature pure silver caps instead of the copper - silver plated - gold plated caps. We recommend you to not touch these caps with your bare fingers to prevent corrosion. If you still would like to touch them, please thorougly wash your hands prior to touching them. We don't stock these third generation fuses because, in our opinion, they sound less good than the second generation...

Be warned for fuses that look similar, but in fact are ordinary fuses with copper-clad endcaps, from which is claimed they should consist of pure copper.

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Straight melting wire consisting of 99% silver & 1% gold Black ceramic tube with special filler Caps consisiting of 99% silver & 1% gold Cryogen treated Demagnetised Available in all common sizes and ratings Only time-lag fuses in stock

In these fuses, the caps as well as the melting wire consist of 99% pure silver and 1% of gold, brought together in a black ceramic tube. Of course, this fuse got a cryogen treatment. They are fully hand-built in Germany and are packaged individually in a luxury box.

Supreme³  time-delayed, 5 X 20 mm: 160 mA, 200 mA, 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A, 1.25 A, 1.6 A, 2 A, 2.5 A, 3.15 A, 4 A, 5 A, 6.3 A, 8 A, 10 A.
 
US-Supreme³ time-delayed, 6.35 X 32 mm: 250 mA, 315 mA, 400 mA, 500 mA, 630 mA, 800 mA, 1 A, 1.25 A, 1.6 A, 2 A, 2.5 A, 3.15 A, 4 A, 5 A, 6.3 A, 8 A, 10 A.

The impact on your sound can best be described as a highly musical and very detailed, dynamic and fast sound. In fact, the good properties of both the Ultimate² and the Furutech fuses come together in this fuse.

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This 10 X 38 mm fuse consists of the same materials as the Ultimate² fuse. It is a good upgrade for the standard fuse of our Cylindric Fuse Cartridge, and for both the copper and gold plated versions of the AHP Klangmodul.  This 10 X 38 mm fuse is only available slow blow: 16 A, 20 A, 25 A, 32A.

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HiFi-Tuning also features the Diazed DII in their program. These fuses are still popular because they need more time to trip than resettable fuses. Many power amplifiers cause resettable fuses to trip early. The use of the Diazed fuse prevents this unwanted behaviour. It is also well-known these fuses simply sound better than resettable ones. The Diazed fuses consists of a ceramic body, which is filed with fine quartz sand. Caps are made from brass and have been silver plated. They have been cryogen treated for an even better conductivity. In addition, the Diazed introduces less distortion and noise. The Diazed DII is available slow blow: 16 A, 20A, 25 A, 32 A.

Reviews:

StereoTimes.com, Januari 2012; "HiFi Tuning Supreme fuses. Fuses? Really?", door Mike Silverton "HiFi-Tuning’s top-of-the-line fuses are a screaming bargain. But remember, you need to test for directionality. It’s important." "A bargain at twice the price."
HiFi Test TV Video, September 2011; "Supreme³ Feinsicherungen, Klangsensation!", by Dipl.-Ing. Michael Voight "We never experienced a tuning for around 30 Euros with such clearly audible results! Ultimately, you may experience an improvement of 100%! Striking, enormous and proven by our measurements it's really true: Supreme³ fuses are worth every penny - you should absolutely try them!"
Inner-Magazines.com, July 2011; "Hifi-Tuning fuses & cryonizing", door Kai EKholm "I refer my first impressions after installing the black fuses: Whow (heartbeat), more midrange in the ‘right’ places, meaning more analogue sound, better transients and more bass control. As far as I know they need very little burn in time so you will hear the difference immediately. Judge yourself!"
HiFi Test TV·Video, Juli/Augustus 2011; "Klangtuning mit Sicherungen", by Dipl.-Ing. Michael Voigt "So ein kleines Teil und solch große Wirkung..." "Bin sehr überrascht, das so etwas funktioniert..." "Der Bass wird präziser und Stimmen einfach runder..." "Hörte ich tatsächlich eine eindeutige und positive veränderung..."
Stereo Times, May 2011; "HiFi-Tuning Supreme Fuses, Fine Tuning For Your System", by Moreno Mitchell "Personally, I would compare their installation to making a major component change. In other words, before you decide to change or upgrade a component, I highly recommend you give the Supreme Fuses an audition. I’m serious."
Positive Feedback # 54, March/April 2011; "Supreme³ Fuses", door Grey Weaver "I've no way to test how effective they may be with more modestly priced players or electronics. If you step up to the plate with more affordable gear, drop me a line with your findings; I'd love to learn what you discover. Most musically and enthusiastically recommended!"
Positive Feedback Writers Choice Award 2010; HiFi-Tuning "...each and every time the SilverStar fuses were placed in gear these fuses took that piece of gear to the next level. Not only does this accessory make a true difference, no system should be without them. I have HiFi SilverStar Tuning Fuses in every piece of gear I own. They are in my humble opinion a MUST have accessory."
Music Emotion, 4/2010; "Tuning maatregelen met invloed", by Werner Ero "Ik denk dat deze zekeringen op zich erg goed zijn en dat er technisch het maximaal haalbare uit is gehaald en dat is een goed iets. Anderzijds zullen ze u ook (subtiel) laten horen hoe het met de gesteldheid van uw systeem staat! Klopt het echter allemaal, dan kunt u met deze zekeringen voor een relatief klein bedrag een subtiele maar daadwerkelijke verbetering in uw weergave bereiken."
Positive Feedback ISSUE 51, september/october 2010; "A Finely Tuned Analog Accessory Trio", by Myles B. Astor "Looking back on the various audio accessories that have passed through the system over the years, the HiFi-Tuning fuses really deliver the goods and for a modest price at that!"
www.audioadvies.nl; "Highend zekeringen en standaard zekeringen vergeleken" "Er is meteen een verbetering hoorbaar in de doortekening van de bas en het middengebied. Kleine details zijn eenvoudigweg duidelijker te horen. Daarnaast wordt de afbeelding beter en de soundstage groter. De hoge tonen worden beter gedifferentieerd, ze hebben meer finesse en detail maar absoluut zonder schel of irritant te worden."
Music Emotion, apri 2008; "Ambachtelijke accessoires en meer", door Jo Mullers "De zekeringen van Ron Kemp zijn een must en voor dat geld mag niemand zeuren. Gewoon bestellen en in het apparaat schroeven en daarna blij zijn."
TheStreet.com, 11/3/08; "New Fuse Makes Stereos Sound Fantastic", by Gary Krkow   "The fuse makes the largest change I've ever heard in my home stereo equipment. Currently, I'm testing a great-sounding system from Resolution Audio (I'll tell you more soon). The system sounded very good with the cheapo fuse. With the HiFi-Tuning device, the system is world-class. The difference is anything but subtle."
Positive Feedback Writers Choice Award, 2007; HiFi-Tuning Fuses   "Never has a product looked so seemingly insignificant, yet has had such a positive effect on my system, as the Hifi Tuning fuses. Yes, replacing the five and dime fuses that come with 99.99% of audio components with these gold, ceramic, and silver beauties, results in a cleaning up and filling out from the midrange on up. Gone is a quite noticeable degree of smearing, glare, brightness, and flatness that I attributed to everything else in my system—but the lowly stock fuses."
Stereo Times, Dec. 2007; "HI-FI Tuning FUSE", by Mitch Moreno   "I highly recommend the purchase of a few Ultra Systems Hi-Fi Tuning Fuses for your entire system. I am convinced you cannot lose by giving these wonderful devices a try. At $29.95 for the small size or $34.95/large sizes, they absolutely have to be one of the best low cost tweaks I have ever experienced."
Stereophile USA, Aug. 2007; "HiFi-Tuning Fuses", by Robert Deutsch "But improve the sound they did, and not just marginally. The PS Audio GCC-100 now sounded clearer, more dynamic, with improved transients simply better all around. The difference was big enough that I didn't feel I had to go back and forth between fuses to convince myself that I was hearing it."
Positive Feedback Online - Issue 32; "HiFi Tuning Fuses", by Francisco Duran "The words liquid, natural, and less electronic are very accurate in describing the sonic benefits of these little gems. There was also a slight improvement in focus across the frequency spectrum. The music shifted to a more natural and whole presentation; as opposed to flat, artificial or bright. Couple this to the benefits described above—sweeter more dimensional mid range, bass slightly more fleshed out and a tad more solid—and you just raised the performance of your system many times more than the cost of the fuses."
Stereophile USA, Feb. 2007; "Go Blow a Fuse"   "These have silver filaments, ceramic bodies, and gold over silver terminations, and damn if they didn't seem to produce a subtle but noticeable improvement in smoothness and coherence. For less thean $30 each (available in various sizes) they're worth trying, if only for the diversionary entertainment."
Hi-Fi+ magazine; "Gold Plated Fuses? You've to be kidding, right?", by RG   "What I can detect, all too easily in the system at home, is their effect on the sound as a whole: less grain, blacker background and more natural colours."