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To accommodate the StereoKnight's specific score card of virtues, I swapped amplifiers for my white Kaivalya monos. Those I knew from experience to clearly favor the passive preamp approach. Their THD behavior between single-ended input stage, push/pull output stage and very complex interstage transformer with minuscule embedded negative feedback requires no massaging whatever. All one wants in such circumstances is an invisible volume control (here the dual-mono scheme adds balance control). But as a connection converter, the StereoKnight had another trick up its sleeve.

Enter Udo Linnenberg's fully balanced €4.500 cdp3. This was a tailor-made scenario to explore StereoKnight's attractive any-which-way RCA/XLR feature by going in balanced and out single-ended.

I also ran a Stealth Audio Varidig digital interconnect from my Weiss DAC2's coaxial output to the BNC input of the Linnenberg to access my iMac library. Disconnecting this cable from the German deck instantly reconnected the internal DAC to the laser diodes for CD playback. This became a rare incident of laser-based superiority over magnetic streaming. Spinning the CD was better than streaming the same file from my iMac using the same Linnenberg DAC. Admittedly that processes shiny disc data by I²S while the incoming signal is standard composite S/PDIF. But that's a story for another review.

ModWright's LS100 valve preamp became the real counterpoint. As expected and thus entirely predictable, the passive's more bracing rawer leaner and more lucid delivery better suited the inherently softer mellower and already fleshy and tonally fully developed 6P14P-EV amplifiers. Inserting one half of a 6SN7 triode per side into this particular signal path increased girth but also applied a fine eraser to sharply drawn performer outlines. This toned down separation power and crispness for subjectively greater distance to the musicians. In matters of perceived speed—energy and excitement—it also stepped slightly on the brakes to sound cuddlier and more gemütlich. These changes certainly weren't huge in magnitude but at this level of execution, nothing in hifi electronics tends to be.

The point of this particular system reconfiguration was confirmation that potential passive aggression by way of injected stridency, brittleness or whitishness would not occur. Even on material deliberately selected for its propensity to get watery, glassy and somewhat hollow, none of the possible passive specters raised their heads. I also detected no aversion of the StereoKnight to drive a 5-meter interconnect. In short, this exceptionally well-made physically attractive chunky box behaved and performed exactly as advertised. In this context that was perfection.

If reviewing a loudspeaker—any speaker—equates to writer's hog heaven where one pulls out colorful adjectives for a personality profile, reviewing a passive preamp without obvious impedance issues becomes the arid desert of writer's block. What to say about mostly nothing? You can only do it by triangulation. That's what I attempted here. The result is neither colorful nor charismatic but dry matter of fact. Active circuits should produce more powerful massier bass, passive volume controls the likely better defined and articulated. Actives could have superior dynamics with larger voltage swings, passives very likely will have superior low-level resolution. Actives nearly invariably have a slight gelatin effect to thicken the stew where insertion of a passive ought to act as a blood thinner. Transformer-coupled passives eliminate ground loops and by virtue of zero voltage gain will lower the noise floor of particularly valve amps, especially those of intrinsically high gain like Yamamoto's SETs. None of this is news or anything you've not expected. That makes it no less true and relevant. It's simply less exciting to write about or read.

The real excitement of this discovery is the price/quality quotient. It's amazingly high. By comparison the equivalent Music First Audio passive I previously owned was an overpriced cheap box with messy internals. James Zhang is to be congratulated for not only addressing as esoteric and niche a category as the transformer volume control but applying himself to the task with this degree of vigor, jewelry finish, feature richness and customizable flexibility. For the right system and owner, one of his passives will be the cat's meow and the perfect solution!
Quality of packing: Good.
Reusability of packing: A few times.
Ease of unpacking/repacking: A cinch.
Condition of component received: Flawless.
Completeness of delivery: Perfect.
Human interactions: Delayed but good.
Pricing: Very high value.
Final comments & suggestions: Clearly marked dual-mono controls double as balance control. Freely combinable RCA and XLR i/o ports allow any combination of balanced/single-ended source/amp. Can drive long interconnects. Ideally preceded by a higher-gain source to be operated with higher attenuation. Exceptional build quality.

StereoKnight website