Trying to stop Musical Fidelity's Antony Michaelson from pumping out new models is like trying to get the Labour Party to stop spinning. At least this time, there's an irresistible hook: 2002 is the company's 20th Anniversary, and Michaelson wanted to mark it in style. Unbelievably, he's repeated the brilliant coup which enabled MF to produce the most highly-acclaimed models it has ever released: the Nu-Vista amps and CD player. He's gone out and found a finite supply of another obscure valve.

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Don't confuse this with some unknown Japanese amp maker finding 16 pairs of some pre-war triode, enough to make, say, eight amps for friends (and a journalist or two). No way: Michaelson buys his valves in the thousands. This time, it's a cache of subminiature tubes designed for military use. But - unlike nuvistors - they need no valve bases; MF's biggest headache with the nuvistor was the scarcity of valve bases. Instead, they are hardwired via five filaments exiting from the bottom of the glass envelope; [See sidebar: What Is A Trivistor Tube?] The Tri-Vista 300 Integrated Amplifier is believed to be the first to use these tubes in a commercial audio product, but I have no doubt that some eagle-eyed and elephant-memoried reader will recall some near-forgotten phono amp or some such which used them, too. To be honest, they looked to me like something you'd find in a valve microphone.

Unsurprisingly, the 300 immediately calls to mind the Nu-Vista M3 integrated. But there are plenty of visual changes, not the least being the removal of the gold trim which made the Nu-Vista look like it was designed to satisfy the aesthetic concerns of a pimp in 1970s Miami. Moreover, there's a new light show, bigger knobs and - overall - a more luxurious look. In fact, the whole thing seems bigger, even though the size is the same as the Nu-Vista's.

For starters, the outboard power supply is a beast at 14x6 1/4x9 5/8 in (WDH), and - as there's no remote power on - you'll need access to it for switch-on. As with the M3, it connects to the main unit via three cables for left-and-right power and a control cable. The 300's back panel contains industrial connectors for the power supply, a bank of phono connectors for five line sources, a damned quiet phono stage (plus earthing tag), tape in/out and pre-out, and two pairs of massive multi-way speaker binding posts to facilitate easy bi-wiring. Though the main chassis measures 19x6 1/4x16in (WHD), allow 20in depth for the fittings. Across the front, sexy in various shades of silver and titanium, are a mere three controls: rotaries for volume and source, and a press button to choose tape monitor. This is flanked by four blue lamps to tell you that the pre-amp and power stages are working properly.

Then there are the feet, which change colours from red at switch-on to orange-y amber when the circuits settle to a blue-y mauve after complete warm-up. OK, so this sounds like sheer recidivism after the move away from the Versace-slave/fashion-whore-gilding tack of the Nu-Vista, a gimmick unworthy of a serious product. But even my most cynical audiophile friends had to admit: turn out the lights and it looks cool as hell, in a Close-Encounters-mothership-taking-off way. Makes me wanna reach for a Thai stick.

Easier to justify is full remote control via a hand-held which contains controls for other MF products, including the forthcoming SACD player. Peculiar, though, is the need to fire it directly at the Tri-Vista for the remote to work, something which made me miss the radio (rather than IR) remote of the Unison Research Unico. My only other complaint about presentation is MF's continued usage - inexcusable after the lozenge-shaped Nu-Vista separates - of sharp-edged heat-sinks which surely break some EC safety law. In future, I will name and shame amplifiers which bear lethal heatsinks; there are no excuses for NOT rounding the edges.

Rated at a ferocious 340W/ch and able to deliver 40 amps of peak current, the Tri-Vista will drive anything you care to throw at it. Hungry though the Sonus Faber Guarneris may be, they never taxed the amp, nor did the high-sensitivity-but-tricky-load Wilson WATT Puppy System 6. Intriguingly - and, I've no doubt, to Michaelson's dismay - I turned up one of those truly unlikely matches made in heaven. It's like this: Michaelson has so fallen in love with the Sonus Faber Cremona that he bought a pair and sings their praises at every opportunity. You'll hear no complaints from me, for I agree. But, while reviewing the 300, a pair of this year's Bargain Speakers turned up, what I believe to be a Wharfedale Diamond 8.1 For Grown-Ups. No surprise, here: the little gem was designed by the same genius who penned the Diamond.

So, a brief aside: Quad's new £500-per-pair 12L is so deceptively 'high end', so big-sounding and robust that hammering it with the Tri-Vista resulted in no broken drivers, no scraping voice coils, no fried crossovers. That it did justice to the Tri-Vista in no way undermines the amp; it merely reinforces the notion that speaker size and price mean little. I just thought you might like to know about another magic package which no retailer in his right mind would ever consider demonstrating, as the Tri-Vista, by virtue of power and price, begs a demonstration with £3000-per-pair-and-up speakers. End of rant.

Effectively a dual-mono design with an absurdly over-the-top power supply and with each channel enjoying its own PCB, heatsink, choke regulation and mains transformer, the Tri-Vista seems incapable of running out of steam. It's quiet, easy to listen to for three-hour-plus sessions, operates with a silky smoothness (you'll find it hard to resist changing sources for the hell of it, just to see and hear the motorised rotary-control in action) and seems immune to accidental abuse, such as switching off the mains at the wall or yanking out a cable in haste. Musical Fidelity addressed all manner of concerns which deal directly with safety and security, as well as with immunity to external influences, so the external power supply is no mere conceit.