Believing your own predictions is dangerous. So all this flapping on about The New Integrated Amplifier that I've engaged in for the past year or so has been undertaken with some restraint. But, hey, the Bow ZZ-One and the Krell KAV300i are real products, not imaginary. They're in the shops, not just on the computer screen. Add to them the reappearance of a Beard integrated, GRAAF's Venticinque (launched at the Hi-Fi Show), the continuing success of myriad Coplands and you can see why trend-spotters might suspect that the humble integrated amplifier has gone from caterpillar to butterfly. But an integrated amp from Audio Research.

Why Krell but not ARC? Conditioning, I suppose. Maybe I thought of Krell as less conservative than Audio Research. So when I and others begged Bill Johnson to pen an integrated - for Europe if not for the USA - he probably assumed KK was munching on the cacti in the Las Vegas desert. But here we have the CA-50. The Audio Research team responded with an integrated which combines their latest thinking with a semblance of cost-consciousness. And it's pure Audio Research throughout, despite the downsizing.

What it isn't is an 'entry-level high-end' integrated, like the Krell or the Bow. At £3990, it's substantially dearer and its release probably an act of greater courage. Until recently, integrated amps meant 'budget systems', even though there have always been integrateds selling in the low four figures. The leap from NAD to Audiolab to Copland to Krell is incremental. Audio Research, according to Terry Dorn, responded more to the increasing demand in the USA for space-saving components with greater ease-of-use and to general overseas demand, as it did to any demand for less expensive products relative to the regular, separate models.

More recently, the lines have been blurred by power amps capable of accepting a single source by virtue of a volume control. Plenty of single-ended triode power amps wear volume controls for direct-driving by a single source. The Audio Research CA-50 (and the Krell, Bow and GRAAF), though, are 'proper' integrateds in that they accept a full complement of sources and feature at the very least muting facilities or tape loops or remote control or other niceties.

But back to the crack about 'courage'. The biggest market in the world is still the USA; for ARC and Krell, it's their all-important home market. And yet the USA does not absorb integrated amps in the way that Europeans (especially the British) do. Americans quite clearly prefer an either/or situation: Either you're a penny-pinching, low-life, scum-sucking peasant who buys a receiver (tuner, pre-amp and power amp all in one), or you're a Real Man who'll only entertain the idea of true separates. The tuner element is what makes the difference, given that Americans have access to an unbelievable number of stations, whereas what little radio we do get (in the UK especially) is a pile of air-borne ca-ca. So radio is not a priority here, hence the popularity of integrateds over receivers. (Think I'm exaggerating? Receivers and tuners have always been the worst-selling components in Europe,)

So it looks like Audio Research, as Krell before it, admitted that its best foreign markets - Italy, the UK, Germany, Hong Kong - are healthy enough to justify the presence of an integrated amplifier. And if the home market doesn't recognise the worth of the CA-50, well, there are enough audiophiles around the globe to buy all that the company can produce...because the CA-50 is the most cost-effective way yet of acquiring the Audio Research sound, short of buying second-hand. And that won't get you the computerisation.

Yes, the ostensibly humble CA-50 shares with the luxurious LS-15 and Reference One pre-amplifiers the microprocessor-driven volume control and source selector. This may be an all-tube beastie, but technically it's very much of the 1990s. All of the toggles, therefore, are of the spring-loaded instant-contact variety, while the two rotaries don't actually rotate. They're spring-loaded, too, and you hold them in the direction you want them to operate. Then again, this unit is fully remote-controlled (except for power on/off), so you'll rarely find yourself using the toggles or knobs.

At a glance, it looks like a current-generation Audio Research pre-amplifier, although heavier at 56lb and larger at 480x180x380mm (WHD). Like a no-nonsense ARC pre-amp, its rotaries handle level and source select, the latter choosing between five line inputs. (One is marked phono, to accept a device such as the company's own phono amps, currently undergoing modification for CE approval.) Again in traditional ARC practice, there's a recess below the rotaries containing four slim switches, for power on/off, mute, record out and tape monitor. And, like the latest generation of ARC control units, the CA-50 offers something of a light show.

When you switch on, the green light above the mute selector flashes for about a minute, indicating warm-up prior to the signal reaching the outputs. This is mildly amusing, in that it might suggest a typical valve amp run-in time prior to audio bliss. Not so. As the CA-50 has been designed for the real world as much as for audio casualties, and as real folks don't want to wait for a half-hour or more for the system to cook, the CA-50 has the distinct honour of being the 'fastest' tube product I've ever used, in terms of reaching optimum playing temperature. Indeed, it was - during the review period - a favourite party trick, switching it on from ice-cold for visitors who wanted to hear it. And every single one agreed that this is one amp which you can treat like most transistor jobs.

Once the light stops flickering, you'll note that each switch has its own green LED to indicate operation, while each rotary is surrounded by a circle of LEDs. Because the remote control only features up/down for source select rather than a button per input, you can't skip from source to source unless they're adjacent to each other; you have to scroll through them. Conveniently, CD is the middle (12 o'clock) position, which is where most people will have it nowadays, with phono at one o'clock and video at 11 o'clock. Volume increases and decreases are indicated by a single dot of light, its arc visible across the room even to these ailing eyes.

Only the massive binding posts at the back, with terminals for 4 or 8 ohm speakers betray the CA-50 as something other than a pre-amp. Aside from the absence of a balanced input (for cost reasons), the back utilises classic ARC practice, with sturdy gold phono sockets for all inputs, plus an extra output in the form of a sub-out pairing for direct feed to a powered subwoofer or crossover. As it's a full-bandwidth signal, you can probably imagine other uses, but you will need some form of external crossover if you want to use it for its express purpose.

Since the CA-50 arrives with the tubes packed in a foam rubber block, you will have to get inside. Alas, for structural rigidity the company fixed the lid with enough screws to secure a split rim wheel, but once you see inside your eyes will widen...like the gap between the channels. This is a beautifully-made device, with plenty inside to justify the price, yet with a yawning gap between the opposing channels to remind you that it's dual mono all the way down to the main power supply. And if you're familiar with current ARC products, you'll recognise its origins.

In order not to mislead you - beware of any retailer who tells you that a CA-50 equals Model X plus Model Y in a single box - I asked Terry Dorn to provide some idea of equivalency. "As far as the pre-amp section goes, there is no direct equivalent in the range. But it a hybrid of the principles used in both the LS-15 and the Reference 1 pre-amplifiers - same microprocessor, constant current sources from the input stage to ensure the balance and the dynamic capabilities, similar operation. In execution, the power amplifier section has more in common with the new VT100 rather than the more similarly powered VT60."

Two 6922s - input stage and driver - and two specially-selected 6550 output tubes make up the per-channel complement, the valves positioned horizontally on separate, opposing circuit boards mounted on either side of the chassis. No kidding: there really is a wide space between them, reinforcing the dual-mono nature and providing extra ventilation, a gap large enough to hold the rubber block which contains all eight tubes during shipping. The circuit operates in push-pull, ultralinear mode, transformer-coupled and therefore needs about as much special treatment as a Japanese 30W/ch solid-state integrated - aside from plenty of heat necessitating an empty space above the unit for decent airflow.

Whether one has left it on for hours in classic audiophile fashion, or switched it on from cold, there's an immediate, inescapable impression: the CA-70 is one of the best-mannered amplifiers on the market. Heard during my tenure mainly through Wilson WATT/Puppy System V speakers with signal courtesy of the Marantz CD-12/DA-12 K.I., that immediate impression is one of warmth, and the impossibility of listener fatigue. Ever. The only way this amp will ever assault your ears is through too much level rather than through nastiness. However modern the innards, this baby has a Golden Age glow that makes you think you found a mint Marantz 8B which somehow contained NOS capacitors.

It shimmers, it glistens. It's so, so that - try though you might - you cannot bring yourself to criticise it for being nice. Forget accusations along the lines of 'rose-coloured glasses', 'euphonic coloration' or artificial sweetness: this amp just wants to be your musical companion. Your friend. Dorn wasn't kidding when he said that Audio Research wanted to make a product for real folks. This is hi-fi without the tears.

And yet the audiophile in you will find satisfaction. To demonstrate the switch-on-from-cold brilliance, I used the soundtrack, loaded as it is with potential shrillness. I mean, uh, Liza Minelli ain't exactly a wallfower. And there's plenty of Germanic treble, odd percussion, whistles, massed voices - you hear everything bar the troops invading Poland. The CA-50 keeps it all in place, the tonal balance never veering from even-handedness, the images (especially the numerous voices in 'Tomorrow Belongs To Me') never crowding each other. Layers of sound remain as separate as the layers of pastry in a well-baked mille feuilles, hold the custard.

Or not. There is a hint of richness, a lard-arse bottom-end which will be familiar to all of those who find the 6550 'too American', too rock'n'roll, too in-your-face. It's not overwhelming, nor is it uncontrolled/uncontrollable. But, while I found the match with the Wilsons to be made in close proximity to heaven, the 50W/ch CA-50 works better with speakers which Dorn identified as enjoying unexpected popularity in the USA, the home of the unfeasibly large speaker system: mini-monitors. Pair this treasure with any Sonus Faber bar the Extrema, with (bi-wired) LS3/5As, the small Apogee hybrids or - best of all - original Quad ESLs, and you can forget any similarity between the CA-50 and Roseanne's tush.

To counter the atmosphere of , I fed the CA-50 an all-British analogue signal, via the EAR 834P, London cartridge, Decca tonearm and Garrard 401, and Bud Flanagan's 'Who Do You Think You're Kidding Mr Hitler?' on Pye 7N.17854. Craig Milnes of Wilson Benesch had dropped by to collect the WB turntable package. We listened. We grinned. We played that scratched, mono single a couple of times in a row. We chuckled some more.

We knew who won the war.

The Audio Research CA-50 isn't the 'best' amp in the world; that's between the Reference 600, the Marantz Project T-1 and a few other heavy hitters. It may not be the best integrated for everyone; some people just can't cope with valves, however convenient they have been rendered. But the CA-50, better than any other current component I can name, manages to address audiophile concerns, vintage cravings, convenience, cost, size, flexibility and high-end aspirations with greater equanimity than I imagined possible. Like the Krell KAV300i or the Bow for solid-state users, the CA-50 is a perfectly-conceived product for a specific niche.

So much for the superiority of separates...