Sugden Masterclass Pre-Amplifier and AA Stereo Power Amplifier Sugden's A21A integrated is justifiably famous, but this pre/power combo is the best they make.

Founded in 1963, Sugden is the longest running privately owned hi-fi electronics business in the country, yet you have to be a committed enthusiast to even know the brand. It's heartening to think that a quality- first company like Sugden can outlive many of the biggest names in the industry without spending a penny on advertising or PR.

One reason that it has been able to weather the lean years in the industry is that it makes almost every element of its components in-house. This keeps costs down and allows Sugden to make as many parts as it actually needs, rather than having to buy 1,000 units because it's 'cheaper' that way.

Sugden's A21A integrated amp is something of a legend among those in the know - it costs less than a grand but delivers a class A sound that will charm the socks off even the most hard-bitten reviewer. The more costly Masterclass range is the best that Sugden makes and consists of CD player, phono stage, integrated amp, preamp and three power amps. Here we have the AA- designated Pre-Amplifier and stereo Power Amplifier, so called because they both operate largely in class A, the operating mode preferred by valve amp manufacturers and brands like Musical Fidelity for its dynamic and tonal qualities. As a result the Masterclass AA Power Amplifier, despite its unusually large casework, only puts forth 50 watts yet emits as much heat as a traditional class AB design of nearly ten times the power. This is the tradeoff with class A designs - they are 'always on' and produce lots of heat, hence the unusually tall nature of the heatsinks on the AA.

Preamps don't need so much power and therefore don't get so hot but there's a standby mode on this one to keep your electricity bills down. The preamp has what you might call Heckmondwike ergonomics - 'like it or lump it' about sums it up, though the solid casework and hefty front plate with their titanium anodised finish are definite plus points. The inputs are numbered rather than named, with one marked B (for balanced), and three of the front panel knobs are dedicated to tape recording/monitoring purposes. The remote control only covers the volume setting and does so in rather big steps - this is mostly because the pre/power combination as a whole has a lot of gain and you tend to use the volume pot at the bottom of its range if your speakers are anything other than plain inefficient.

The existence on the back panel of both single-ended and balanced in and outputs is much less valve-like and positively helpful. The AA power amp has a matching pair of inputs with switching between them and some reassuringly hefty multi-way binding posts for the speaker cable.

On the inside, Masterclass components use gold-plated PCBs with silver soldered connections and silver signal wires, balanced circuits, current feedback line stages, relay switching and low impedance power supplies. These are all good things where sound quality is concerned and account for much of the substantial cost of the finished units. The only grumble with the power amp is its height - at 25.8cm including feet it is too high for many standard racks.

Sound Quality

The Masterclass AA pre/power is one of the most organic and dynamic transistor amplifiers you can buy, and the similarities to (good) valve amps are uncanny. The strong biasing into class A is clearly a major factor here, and is almost certainly the reason for the uncanny dynamic transparency on offer. Another reason might be the fullness of the bass - this could be where the earthiness comes from, as it adds a certain richness that makes wooden instruments sound more real. In fact, all instruments (and voices for that matter) are more convincing than usual with this pairing. When it comes to tonal rendering they are distinctly unlike most trannie amps, which on the whole tend toward a dry balance, delivering bone-crunching bass at the expense of texture and body.

We used the Sugdens with Living Voice Avatar OBX-R2 and Focal-JMlab Micro Utopia Be speakers, as tested last month, and both pairings worked well. We expected the Avatar, which also excels in the dynamic and tonal departments, to be a good match but were quite surprised at how the Micro Utopia Be literally sprang into life in the Sugden's company. In fact, the first impression this amp pairing gives is of liveliness - it has a remarkable ability to reveal the energy in the music, opening up even the most dense recordings to tremendous effect. Not all recordings are equal of course, and you notice this much more than usual, the dynamic transparency in effect revealing the degree of vigour in each track. The acoustic material on Led Zeppelin III worked particularly well off old vinyl, Page's guitar delivering that new string zing in a way that even 200g audiophile pressings struggle to reproduce.

Likewise, imaging is linked directly to the quality of the source yet the power amp doesn't have quite the depth resolution available from the likes of a Gamut D200 (at a similar price). This comparison is very interesting. In fact, the Sugden scores in terms of richness of tone while the Gamut reveals more space and seems to be more transparent but leaves you wondering if it's not putting a sheen over the textures that the Sugden paints so vividly. What is obvious is that the bass on the Yorkshire-born design is fuller and not so deep, a balance which suits something like the Micro Utopia Be down to the ground but might not be appropriate with bigger or more current-hungry loudspeakers.

Timing is also a strong point. There's no undue emphasis on leading edges but the music seems to flow particularly well and you find yourself involuntarily nodding along (well, some of us do). Put on some Esbjorn Svenson Trio piano-led jazz and you'll get straight into the groove while marvelling at the lovely sound of the instruments. The piano almost literally shines while you can hear right into the double bass and fully appreciate the drummer's brushwork. This is due to the Sugden pairing's very strong harmonic resolution, very much a tube trait and one at which the better tube designs are slightly more adept (but only slightly). Listen to the way notes decay on these amps and you'll wonder why on earth more transistor amp designers can't do the same thing, as very few, if any, of them can.

When looking to partner these amps, look for a source that can feed their strengths - the Resolution Audio Opus 21 CD player for instance, or a Classé CDP-10. For vinyl, consider the best works from the likes of Michell, Avid and SME. And for comparisons, try to track down a Border Patrol P20 power amp or a Pathos TT RR, another class A trannie design. Some of the midrange Classé amps would also be interesting to compare.

But it's unlikely that any of those above will have quite the same combination of dynamic expression, tonal richness and musical engagement on offer from the Masterclass AA pairing. These amps combine the strengths of trannies and valves in a way that is rarely encountered, which makes for highly distracting entertainment. If you haven't heard your favourite albums through an amplifier like this, then you just haven't heard them.

Jason kennedy Features Size (WxHxD): pre 43x7.5x32cm, power 43x25.8x31.7cm Weight: pre 5kg, power 20kg Class A power output 50W/8ohm Inputs: 4 line, 1 bal, 2 tape, outputs: single-ended and balanced