Anthony Michaelson knows how to push the right buttons. All he had to say was the word 'nuvistor', and every tube crazy worth his weight in anode plates was clamouring for a listen. After all, wasn't the nuvistor the last-ever, all-new tube, conceived just as the transistor turned life into shit?

'Last-ever all-new tube' - strong words. But they're true, and all of those 'KT' variants, the myriad 300B derivatives...they're not all-new tubes but modified alternatives souped up for modern needs. (Think about it: the guy who comes up with a 300B which puts out some serious wattage and doesn't have bass like a whoopee cushion can order his next Ferrari.) The nuvistor was/is the missing link between valves and trannies, a 'sub-miniature triode' that's all-tube, only teensy-weensy. Like the up to the first joint of your little finger.

And it is a tube, not a transistor, only one encased in metal. The 6CW4 nuvistor triode is roughly equivalent to a Lilliputian ECC88, the '88 being one of the most highly regarded pre-amp tubes in use today. Now, imagine if you could enjoy the bliss of an ECC88 without the size, the fragility, the heat - you know, all of the stuff which transistors offer while throwing away the sound.

Designed for use mainly in military applications and for measuring equipment such as oscilloscopes, the nuvistor was metal-clad to provide magnetic shielding, and its other qualities included low noise, low microphony, terrific linearity, consistency, long life - you know, everything which could combine the create the ideal 'fantasy' valve. So why wasn't it a success?

Simple: bad timing. In the 1950s, solid-state technology was rearing its ugly little head, and it quickly developed into the cool-running, low-cost alternative to something which makes music. Had the nuvistor arrived 10 years earlier, it might have been a different story. Anyway, the nuvistor was all but ignored by the audio industry, and the only company which I have been able to identify with any certainty as having used it is conrad-johnson.

Current importer Audiofreaks confirmed that c-j used nuvistors in a range of moving-coil step-up devices, the now-covetable models HV1, HV2 and Premier 6, each with two nuvistors per channel. Branko also believes that the Premier 7 and Evolution 20 were nuvistor-bearing designs, but that's it as far as audio uses are concerned. (Readers who know otherwise: letters to the usual address, please!) And the nuvistor would have remained nearly-forgotten until Anthony Michaelson was reminded of its unfulfilled promise. So he went out and pretty much bought up the world's remaining supplies.

His travails in merely acquiring enough nuvistors to make sufficient numbers of a specific model would make interesting reading, but space precludes it. Suffice to say, none of the tube suppliers took him seriously until he produced the funds up front to prove his intent. Hey, presto - thousands of the little gems were suddenly on their way to Olympic Trading Estate, enough to put four in each of the 500 examples he will produce of the Nu-Vista pre-amplifiers, with Musical Fidelity keeping in storage a complete set of replacement nuvistors for each one; this accounts for 4000 of the little bleeders. And with nuvistors enjoying a life estimated at around 100,000 hours, well, MF reckons that's good for 12-15 years. So, even with heavy use, Nu-Vistas on the second set of nuvistors should be working until 2025. If the planet's still working.

So, unlike other artificial 'limited editions', the Nu-Vista is a genuine collector's item, its numbers restricted because of the availability of key components, not some marketing man's notion of a lucky number. Anthony admits that he was inspired in part by various watch brands -- Chronoswiss and Oris, for example - which discovered small, unused supplies of vintage mechanisms, creating new models to house them, all severely limited due to the number of original works.

So what has been wrapped around this quartet of My Little Pony tubes? A Pure Class-A Pre-amplifier. But this is no hair-shirt atrocity aimed at psychotics. Hell, no. Think back to June to the X-A1 review, and how cool and funky was that extruded lozenge-shaped delight. The Nu-Vista is housed in the same enclosure, only with its power supply in a proper X-Series cylinder instead of a cheapo-cheapo black plastic lump. And the two look just right side-by-side.

Nu-Vista provides five line level inputs, a tape loop and a phono section derived partly from the X-Tract, all fed by gold-plated phono sockets. Its hands-on operational bits consist of volume control, tape monitor button and source selector, with power-on courtesy of a button on the front of the power supply cylinder; the latter connects to the main chassis through an umbilical cord with a locking XLR-type plug. At 230mm wide, the Nu-Vista, like the X-A1, has been styled to resemble two Siamese-twinned X-Series cylinders.

Also as per the X-A1, the styling, dimensions and electronic specification allow Nu-Vista to work with X-Series modules, as well as the X-Site links which let you link these components horizontally and vertically. Only this time, there's one less X-Series module to consider, given the Nu-Vista's built-in phono section. Still, if spending is your disease, you can add an X-Series DAC, a headphone amplifier, X-10D buffers, an equaliser or any other modules. (Note that Musical Fidelity might be producing another type of dedicated equipment rack for X-Series and Nu-Vista models, for those who'd rather not stack 'em up with X-Sites.)

But the Nu-Vista is no hi-fi-for-the-fiscally-challenged, pocket-money tchatchke. No way. To add a touch of elegance, to distinguish it from its bargain-basement siblings, the Nu-Vista features sculpted recesses around all of the controls and lights, the press buttons feel nicer to use, the knobs are like jewellery, and - dig this - the Nu-Vista is fully remote controlled. With both the source selector the volume control motorised. Neat stuff, eh?

OK, OK, so I was already predisposed toward the Nu-Vista because, (1) the nuvistor element fascinated me and (2) I adore the X-A1. And OK, OK, so maybe I to like it because it was brave and daring, and I just those extrusions. I liked the way the lights are sunken into the fascia, the way everything clicks so nicely. I loved the notion of only 500 examples being made. I like the way customers are being protected, with the replacement nuvistor sets costing only £32. But penny-pinchers, take note: fiscal foresight on MF's part has established a fixed rate of inflation to be added at 7.5 percent per annum after 1998. Which is me telling you to buy a set of spares when you buy the pre-amp itself...

Warm-up time for the Nu-Vista was the same as for any valve or (solid-state) Class A product, the sound improving and then settling in nicely after a half-hour. Still, I kept it on the entire fortnight it was on trial just for simplicity's sake. Sources fed into it included the Basis 2000/Rega RB300 turntable/arm combo with a Grado Prestige cartridge, a Krell KAV-300cd CD player and mix of amplifiers. At various times, the Nu-Vista drove Radford MA-25s, the Unison Research Power 35, Musical Fidelity X-A50s and Quad IIs. Speakers? Quad ESLs, LS3/5As and New Audio Frontiers Reference One S.

It's not what you expect. Hell, nothing can prepare you for the Nu-Vista, because hardly any of us really knew what a nuvistor could do, outside of the aforementioned c-j phono duties. And it isn't even the Nu-Vista's phono stage - set up for moving magnets and high output m-cs - which impresses the most. Sure, it has bags of headroom and it's deathly quiet and uncoloured. But that applies to the entire Nu-Vista experience. Quite simply, the Nu-Vista undermines every product (and, for that matter, every review) which has been based on achieving successful sonic marriages betwixt tube and tranny. You know the drill: certain modern MOSFET designs which emulate valves, certain valve designs which possess solid-state control.

And hasn't that been the basis of the quest for the last 30 years? To find an operating device which gives us - truly - the best of both worlds? Haven't all of us been looking for a solid state amp with valve's musical virtues and gentle clipping under duress, or valve amps with a transistor's control down below and ghostly silences when required? The slap in the face, the irony from which we should never recover, is that the nuvistor had it all.

At the risk of upsetting those who think nuvistors are crap (and a couple of my valve-lovin' heroes do think that nuvistors horrible), I have to say that I've never heard a more harmonious blending of warmth detail, silent running richness, seemingly unlimited dynamic capabilities total control. I reverted to favourite torture tests like Willy DeVIlle's 'Assassin Of Love', B.B. King's take of 'Don't Get Around Much Anymore', Jeff Beck's 'Ain't Superstitious' and Big Daddy's 'With A Little Help From My Friends' to hear if there really was more on offer. And sure enough, I was able to listen the performances and explore their sonic spaces as if using a 3-D computer sim with perfect 'virtual reality'. Think of one of those museum 'tours' on CD-ROM, or some state-of-the-art computer game. Only this is a sonic world not limited by a 19in screen.

But the sound! Life-like vocals with all of those little clues: the sound of tongue touching teeth, breathiness, smooth 'S' sounds. Bass with just the right resonance, yet no overhang. Acoustic guitars with woody ambience. Brass with punch and sparkle. But most of all, a sense of effortlessness which allows music to flow, yet with enough control to keep it in check...as required. The Nu-Vista is, if you'll forgive this rather sordid analogy, both your slave and your dominatrix...

Of course, achievement of this total bliss depends on a system as a whole, one with superlative resolution, and you can get damned close with other pre-amps. Like Audio Research's Reference One, the Krell KRC-HR and a few other high-end contenders. So read this next bit closely, and note that there really are only two zeroes in the figure: the Nu-Vista sells for £1200. One-thousand, two hundred pounds. Which is a bargain for decent remote control tube pre-amp, let alone one this blindingly superior.

Now the serious stuff: The first 300 were pre-ordered before production commenced, so move quickly. The 500-only run of the forthcoming hybrid power amplifier - 300 watts! 100amps! -- uses up the remaining supplies of nuvistors and it will be offered first to existing Nu-Vista owners, giving them the opportunity to buy the units with the serial numbers matching their pre-amps. Only those not taken up by Nu-Vista pre-amp owners will be made available for the rest of you. Horrible thought: What if all of the original 500 Nu-Vista owners opt for the power amps, and someone wants to bi-amplify?

By the way, I placed a firm order for a Nu-Vista within one hour of switching on the review sample. I asked for serial no. 046. Oh, and I have already started saving for its partnering amplifier.