The ultimate sleeper, here was a great sounding solid-state power amplifier at an affordable price, built like the proverbial brick wash room and finished to the standard of the finest Japanese hi-fi. Trouble is, it was made in South Korea by a company that no one has ever heard of in the West, and consequently it bombed. Claimed to drive practically any load, here was a sweet sounding transistor amplifier that delivered toe-curling power into awkward loads, yet sounded open and organic across the midband – and cost just £1,495 when new in 2004.
This beastie promised 200W per side, with bridgeable monoblock operation going up to 600W “without breaking into a sweat”, according to April Music – the company behind the Stello Brand. The power amp stages comprise four pairs of J-FETs (push-pull parallel output circuitry with SANKEN MT-200 power transistors) with custom-designed non-polar coupling capacitors and fully balanced circuitry – including bias stabilisation, ‘sound correction’ and multiple protection circuits. In the power supply, a chunky 1,000VA custom-made transformer is used with a capacitor bank of 180,000uF.
The Stello is superbly finished, as per its excellent partnering DP200 DAC/preamplifier, in the familiar brushed aluminium (435×94.5x345mm) case weighing in at a healthy 14kg. Round the back, there’s one pair of unbalanced RCA ins, one pair of balanced XLR ins, 12V Trigger (RCA) and some rather odd looking, albeit substantial speaker binding posts which only accept banana plugs with a bit of lateral thinking… The balanced XLRs are easily selected by flicking a small ‘dip switch’ at the back, one per side. Stereo-Bridged operation is achieved by a similar action. A switched IEC completes the package.
Sonically its all round ability at the price is quite something. Essentially, it has an open and expansive character, with very little in the way of upper midband hardness. At the bottom end, it’s a strong and confident performer, whilst up top it’s smooth and detailed. Zero 7’s I Have Seen showed this device to best effect. The opening bass sequence proved it to be fast and lithe downstairs, with a strong and insistent low frequency performance which never once hindered the rhythms of the song. Indeed, it’s a surprisingly subtle and fluid performer. While this amplifier never feels completely in the groove (and I don’t know any solid-state designs that do), it nevertheless has real rhythmic acumen, giving the song an intricate and involving feel.
Moving up the frequency band, and the S200 is detailed and fast, yet doesn’t fall over itself to recover low level information, losing the musical plot in the process. Rather, it conjures up a large and well proportioned recorded acoustic, with an expansive stereo image and fine stage depth too. Isaac Hayes’s Cafe Regio’s was a great test of its transparency, and the S200 did very well. Once again, bass was strong and taut, midband delicious, and horns and strings delightfully smooth – with only the slightest hint of wiriness that you’d expect from a solid-stater.
Beethoven’s Symphony No.9 gave an enveloping sound, with good depth perspective. String timbre was surprisingly natural – obviously this is no high end tube amp in this respect, but the S200 gave a real sense of the timbre of cellos and violins without lapsing into harshness. Up top, the Stello boasts an accomplished treble too. It’s open and smooth, yet doesn’t get overly silky like certain Japanese high end. There’s great speed and bite with Kraftwerk’s Tour de France – the hi-hat sound proved extremely percussive, whilst satisfyingly sweet too. Kate Bush’s Moving showed how seamlessly it moved from the midband to the high notes, with a refreshingly naturalness.
April Music’s Stello S200 has an all-round competence that impressed me so much. Few if any price rivals at the time of its launch fifteen years ago served up clean, smooth transistor power in such quantity. None were as well made at the price – and factor in exquisite build and it was a true audiophile bargain. Because they never sold in any numbers in Europe, they’re few and far between, but if one pops up secondhand for around £500 then don’t hang around!