The Sugden A21a is something of a living legend, a Class A integrated amplifier that has been in production for over 20 years, but whose earlier incarnations date back as far as the sixties.
It has maintained its appeal thanks to a sound that can charm the pants off the most hardbitten of reviewers and inspires genuine affection among its many users. However, time would seem to have caught up with it in many respects, and Sugden Audio felt the moment had come to bring it up to date, albeit while attempting to retain the characteristics which have won it so much admiration.
The brand new A21a is not particularly well differentiated on paper; the name has been extended by the letter L in upper (line level) or lower (phono) case and the words Series 2. Marketing was clearly not at the forefront when this revision was conceived - in fact, judging from the stealthy approach that Sugden takes to all forms of promotion, we suspect it's a dirty word in that part of Yorkshire.
However, there have been significant changes both internally and externally to this solid integrated amplifier. As you can see, the front panel is no longer made of bent steel but 10mm-thick aluminium with chunky machined control knobs to match.
It's a faceplate style that'll be very familiar to anyone who has seen the A21SE or any of Sugden's Masterclass series, and one that's a dramatic improvement on its predecessor. It's not just a facelift, though - the chassis is 50 per cent thicker and made out of a single piece for increased rigidity.
Possibly this was a necessity brought about by the introduction of a beefier power supply, one that means the A21a's output is no longer compromised by speakers with a four-ohm load.
The preamplifier section has also been completely reconfigured and sited behind the fascia in order to reduce the length of the signal path.
The overall circuit has been straightened by removing the tape-monitor and mono-switching options of the previous model, facilities which some people will no doubt miss, especially given the scarcity of mono switches on contemporary amplifiers.
But if the result is worth the candle, so to speak, then it'll have been a worthwhile sacrifice. Another victim of the straight lining process is balance control, again something that has become a bit of a minority interest these days, and something we only ever use to check for a fault.
Sugden describes these various changes as evolutionary, but the removal of three functions strikes us as being closer to radical, more so even than the cosmetic revamp. However, the model still retains the horizontal cooling fins along its flanks, and there's the option of adding an MM/MC phono stage for a very reasonable £100, though this does take up one of the five line inputs.
Another radical change is the introduction of remote volume control, something, which in our view, more than makes up for the features lost. Remote input selection would also have been nice, but this is still a proper 'hair shirt' product.
So much so, in fact, that there are no input markings on the front panel - you have to find your source blind, though the radial nature of the inputs means that you soon learn where they are.
As previously mentioned, although the power output remains at 21 watts per channel, the increase in power-supply stiffness means higher current is available, which makes for greater control over the loudspeaker load.
It's still hardly a bone-cruncher in power terms, but its Class A operation means that when it runs out of steam it does so in a far smoother style than Class AB amps, which is why low-powered valve amps get away with so much. Nonetheless, speakers that have higher sensitivity are always a good idea with most Class A designs.
One practical advantage of Class A is that the amp warms up very quickly, and within half an hour is too hot to leave your hand on. This isn't exactly economical, but Sugden does suggest you turn it off when not in use, which means it probably has a similar carbon footprint to an AB design that's permanently left on.
Having said that, an easy load would be best for the A21a. Given a spin with the mighty B&W 802Ds in our listening room, it doesn't seem phased by the task, so long as the volume is kept to a sensible level. The pairing enables the amplifier to show off its delicate touch through the midband, one which brings forward subtleties of the music that aren't usually apparent with more powerful amps.
It produces a big-boned, bold piano sound with good low-level resolve and a smoother top end than that of the Pioneer A-A9 (which is less than half the price).
Moving on to a more natural loudspeaker partner in the form of Living Voice's Avatar OBX-R, with its higher sensitivity and easier load, it becomes apparent that the new A21a isn't quite as romantic as its predecessor.
It's still very sweet, but it's also more even in balance and extended at the bandwidth extremes; the bass has a bit more weight to it and the highs don't seem as smoothed off. Which is a step forward in terms of fidelity and one we applaud, but it does bring this amp a bit closer to the norm.
However, the Class A factor saves it from being just another integrated model, while the midrange is glorious and voices have so much depth and timbral colour that when they belong to the likes of Diana Krall they take on a new allure.
What the changes seem to have brought to the party is a greater fleetness of foot - this Sugden has a great sense of timing and draws you into the groove before all else. That's something we don't remember being so clear with its predecessor.
It also retains the sense of life in the music, the energy that makes Class A so appealing. Instruments sound dynamic and real and take on a three-dimensional solidity in the room - an effect reinforced by the high level of detail that the Sugden is able to deliver and underpinned by a bottom end that has something approaching grip when the load isn't too challenging.
But stick on something more weighty, such as the beats of Missy Elliott, and you can hear the limitations of those 20 watts. If you want to bomb the bass, then there's no substitute for power.
This is demonstrated quite ably by Russ Andrews' HP-1/PA-1 pre/power amplifier, which offers 55 watts and delivers the fourth dimension - bass - in relatively arse-kicking fashion, albeit in the context of a two-box system with only two inputs and no remote.
The A21a presents a more upbeat and effusive sound that's more lyrical and arguably more enjoyable, even if you don't feel it so strongly in the sternum. It's extremely communicative, and given that music is a language of sorts, this is a key strength.
Giving the Sugden a final crack with Tannoy's pretty efficient Glenair 10 speakers (reviewed last month) reveals that they make a great pairing. The amp's strong dynamics play to the speaker's strength, and its smooth highs offset the slightly exposed nature of the speaker's treble. More importantly, they both pull in the same musical direction to produce a totally engaging experience with a superb sense of presence.
The Sugden A21a has, we're glad to say, managed to up its game without losing its magic touch in the communication department. It may not be as romantic as its forebear, but it's still pretty sweet by most standards. This, combined with the wholesale improvement in looks and build, means that it remains as potent a force for musical good as ever.