The "trouble" with properly designed preamps? Their bleeding Swiss neutrality perhaps? Check. Such civil behaviour can go very much unnoticed. The interfaces between amp+speaker then speaker+room suffer greatly from nonlinear Ω, back electromotive force, uneven radiation patterns with skewed power response and assorted room ruinations. Complex reactions and interactions influence frequency response, damping, dynamic expression and more. Most of it is unpredictable. That's the chewy stuff reviewers can sink their teeth into. Meanwhile any preamplifier aka volume control aka switcher that was not designed to prettify or otherwise alter the sound according to a designer's willful notions ought to be interchangeable with any other. That's big trouble if you're a writer who chases differences to have something to write about. That's big trouble for sellers who insist that their very costly preamps beat your far cheaper one. How to, in the first place, recognize neutrality in all of its more-or-less glory is still more troubling. A straight-wire bypass would do but we'd still need some practical means to set volume to something useful. Most of us can't. So really, the only ones not troubled by any of it are the claimants of "all equipment that measures the same sounds the same". If only.

The rest of us blessed/cursed with more imagination must compare and contrast. Just so, all our fancy footwork shuffles inside the ring of the unholy amp-speaker-room trinity. It's thus inextricably coloured by it. As Shinobu explains, this even happens to traditional transformer passives when they slip between sources and amps which use DC-blocking capacitors. Together with the volume transformers, those generate "a CLC resonator with an undesirable influence on frequency response and phase". Preda's DC-coupled buffers bracket the Slagleformers to eliminate that behaviour. To kick off my Swiss mission, I'd contrast Shinobu Karaki's neutrality to Vinnie Rossi's. Roger Federer against Stanislas Wawrinka. Team Lio only plays single-ended hifi tennis. I'd first run Preda in equal fashion, admitting that it might compromise this unit's all-in performance of fully balanced which bypasses two 'conversion' stages (turning single-ended input signal into balanced, then the buffered balanced output signal back to single-ended). That exercise in contrast would square off Slagles vs Slagles. The other differences were buffered vs unbuffered; and a linear supply on the control circuitry vs ultracaps for full power-grid decoupling. Would I hear Benetton's many rainbow colours of neutrality; or see all-white tennis dress code?


If neutrality be exclusive to frequency response, both units were as blood-brother equal as my ears could discern. Yet they didn't sound the same, exactly. There's more to audio performance than frequency response. In my single-ended context, Lio had the slight advantage in power of contrast. Its frisson of sounds against silence—some call this image pop—was a tad higher to notch up contrast ratio by a click or two. Images popped more strongly to enhance the illusion of recorded space manifesting in our place. To be sure, this was subtle but once cued into, quite repeatable. This really surprised my inner accountant. It enforced a quickie visit to Vinnie Rossi's website to confirm $4'985 as the cost of a Lio configured as Slagleformer passive. Entering the TBSP's £15'999 sticker into xe.com's currency converter netted $23'300; about 4.5 times as much. Of course it absolutely crushes Lio on inputs. But frankly, 10 inputs are excessive for most. That left the promise of true balanced. Here the reader notes that comparing Preda SE to Preda XLR couldn't happen in isolation. It also meant exploiting the Aqua Hifi LaScala MkII source and Pass Labs XA30.8 amp in XLR mode to involve rather more variables. Whilst I could comment on whether a fully balanced transmission front to back sounded better or different than going it single-ended, this wouldn't be a categorical statement. If for example a source were single-ended with only a convenience XLR output; or one generated with op amps for phase splitting; it might sound slightly better tapped via RCA. And so forth. There are numerous elements to consider; and whether associated components sound better tapped/driven in SE or balanced mode.
Presumably current sources, four orange LEDs inside bleed through the meshed lid openings to suggest traditional valves. This makes for quite the coloured light show with a red display, green gain switch, orange faux-tube glow, bright blue and pink/purple power supply lights (plus another purple polarity light on the head unit if engaged). Conservative Japanese this is not but the power supply diodes do match the logo. Given how even the designer calls this model a custom edition, one presumes that clients might have a say if they desired a different more unified light show. The display itself can't be extinguished because Shinobu reprogrammed that particular button on the remote to control polarity inversion.
Squaring off the Preda against itself had XLR clearly lead the way. It sounded spatially more expansive, materially more robust and in general slightly more explicit about fine detail to now exceed the Lio showing. (Again, this could have meant, at least partially, that my DAC and/or amp sound better in XLR mode, not this preamp.) My own takeaway from this first session? 1/ John Chapman's Slagleformer tech is very mature. Even without a buffer follower as in the Lio, it's capable of driving 6-metre interconnects without audible losses. 2/ If one ran single-ended components around the TBSP, the Preda could react slightly handicapped. For certain, it now becomes raging overkill. 3/ Its i/o buffer scheme guarantees invariable results no matter the unpredictable mix of source output impedance, amplifier input impedance and autoformer impedance fluctuating with volume setting. An unterminated solution like Lio can be its full equal if its partners tango happily; or might not if your usage were suboptimal with impedance interactions. Whether possible sonic shadows of such interactions can justify the high cost of peace of mind which Shinobu Karaki offers remains the big open question. To my mind, there's absolutely zero question however on how to properly use this twin boxer: balanced all the way! Back to neutrality being colourless, pale and washed out because we reflexively associate it with sterile hospitals, that's bad misdirection. Neutrality just means giving what's upstream a free pass, no sticky strings attached. If you start out with good recordings, you'll clear all the colour intensity and tonal beauty you could desire, no extra seasoning required. Back on tennis tournament dress code, forget boring white. Think Serena Williams instead. With the Preda TBSP, our system sounded truly terrific. How would it differ from the tube-based Nagra Jazz? Mine has the optional transformer-coupled balanced outputs. At its time, it sold for roughly the same as the fully balanced Preda does now.


On the old pennies for parts perception, the two-box Preda entered this session the obviously bigger, heavier bruiser from the start. Anyone needing maximum physical evidence—money translated into material substance—would consider Aurorasound's return on investment more loaded. Whilst the Nagra too gets an outboard power supply, it's puny by comparison and meant to hide behind the equipment rack. Even its main chassis is small and lightweight against the stuffed-to-the-gills Japanese tank. Onto sonics. Those often reward simpler less parts-intensive circuits. That creates friction, between those who shop hifi with their eyes versus those who solely rely on their ears. Finally, the Nagra is a tube-based device. We might think that its overriding design focus must have been musicality, not neutrality. Whilst that distinction can encapsulate particular perspectives and sonic aesthetics, it can also prove to be an entirely artificial division when it leads to the very same place.


And so it was. Both decks played on the same elevated plateau. The differences were smaller than what their respective circuit choices hoped to predict. Just so, the Nagra's textures were a bit softer, its lighting a touch yellower. The Aurorasound felt shinier; more crystalline. Because our new two-storey vaulted ceiling's longer decays infuse music with more playback ambiance despite a speaker setup deliberately away from the walls, close to the chair and steeply toed in, the Preda traits had my nod. Dynamically, it also felt twitchier. The Taksim Trio II's chamber music setting made more ripples. It was microdynamically splashier and even more expressive. On soundstage layering where tubes often excel, I heard zero advantages for the Jazz. Whilst tonally it arguably was very slightly thicker, in our more reverberant space, this wasn't the gain it can be in overdamped acoustics with their desiccated tone. Actually, the Preda qualities I kept returning to were its textural shininess; and how its enormous spaciousness was very finely crystallized and specific, not vague or smeared. Lucid mode aka electrostatic transparency is a core quality for when passive preamps are happy. Dynamic expressiveness usually isn't to the same extent when gauged against a superior active preamp. Connecting both disciplines is where the Aurorasound stood out. It really behaved like a passive with brass balls.


This combination of the illuminated/explicit with the dynamically energetic reminded be of the trim twins of clarity and speed which often appear with wide bandwidth DC-coupled amplifiers. Which of course is exactly what the Preda circuit is as well. In that sense, its circuit descriptions match the sonic realiTy to a 't'. Given how much truly balanced gear exhibits twice the gain over its RCA paths, Shinobu's low-gain switch was eminently helpful. Now things didn't get too loud too soon. And you'd be surprised how quickly it gets loud even with 85dB speakers in a 90m² room when source output voltage is 4.8V on XLR and amplifier input sensitivity 1V or lower. Instead of being too intense at already 10 on the dial, low-gain mode now extended useful range up a lot. Super practical, that!
Top-quality socketry.
Predatorial. A sonic tutorial for the Preda would call it an uncompromised passive on sheer transparency. Uncompromised means zero impedance/drive issues no matter the ancillaries including cable lengths. On speed, drive and control, it switches gears to behave like a high-gain wide-bandwidth circuit. That implies no signal-path capacitors and no phase shift. To the ears, it's a not exactly common 'hybrid'. Add superlative build and comprehensive functionality. It all delivers a complete package. The only real proviso, coin excepted, is that its true balanced architecture mandates also using it in the context of a fully balanced system to get its best and cash in fully on such a serious investment. This really is extremist hifi at its best!
 

Aurorasound website
UK importer's website