Soulnote A-2 integrated amplifier
Soulnote came to my attention when speaker design guru Karl-Heinz Fink used their amplifiers to launch the Epos ES14N at the Munich High End show last year, this demonstration and the one in the Soulnote booth suggested that they know a thing or two about making an engaging sound. Both systems had an immediacy that was thrilling, and under the trying circumstances of an audio show this is quite an achievement, I was keen to hear more. Soulnote gained UK distribution and were at the Ascot show earlier in the autumn, this cemented my interest and I requested a sample to try at home. I’m glad I did.
Soulnote is not a new brand, it was formed by former Marantz employees in 2004 and is led by chief sound manager Hideki Kato whose CV includes the last serious audio components made by Philips (LHH series) and amplifiers for NEC. Kato’s engineering life has centred around trying to find why measured results do not correspond with sound quality, he cites two technologies that measure poorly yet sound good; non-oversampled PCM in digital to analogue conversion and non negative feedback in amplifier circuits. Neither measures well in a static situation but in the dynamic replay scenario they yield better sound.
Soulnote strongly believes that the time axis is the most critical for accuracy in musical reproduction but have not found a way to accurately measure it, thus the research and development of Soulnote electronics is done by ear. This is quite a popular approach among the boutique brands but is far less common for engineers schooled in the world of mass production.
The A-2 is Soulnote’s midrange integrated amplifier yet it is a beautifully built and finished piece of electronic engineering that would likely cost twice as much if made by a smaller company. It costs a third of the next model up in the range, the A-3, yet has a notably higher output in Wattage terms, clearly Soulnote do not consider power to be a factor of quality either, which is not something many are prepared to admit. The A-2 is rated at 100W into eight Ohms and will double this into a halving of load, which in itself is a rare thing in any integrated.
The Soulnote A-2 contains what they describe as a ‘ferocious power supply’ based around a 600VA toroidal transformer that is wound to the company’s precise specifications. This drives the negative feedback free circuit on a four layer PCB with directly soldered connections rather than plugs, and no shielding or filters in order to reduce the potential for vibration from connecting cables etc. It’s probably not a unique approach but not something that many other companies talk about in this fashion. The volume control is a relay based balanced attenuator rather than a potentiometer, which is a popular approach with high end preamplifiers but less common on integrated designs. The output stage consists of four high speed transistors per channel that are selected and paired using measurements devised by Soulnote in order find the best matched devices regardless of operating temperature.
Ins and outs
The Soulnote A-2 is a line only analogue amplifier, it eschews digital connections, Bluetooth and headphone outputs to concentrate on the meat of the musical matter. It does have plenty of inputs though, with three on single ended RCA and three via balanced XLRs, these sit above the speaker terminals and beside an unusual array of switches. These change the A-2 from an integrated to a power amp, and when the latter is selected into a stereo or mono amp with two modes of operation: BTL (bridged) and bi-amp. It seems a bit dangerous having such an easy to flick switch that removes the volume control from the signal chain, you might accidentally end up having full power from a source rather than a preamp getting to the speakers. But the front of the amp changes significantly as well, in integrated mode it shows which input is selected and volume level in the display, in power amp mode only the power button is lit up, so you can tell that it’s no longer offering preamp functions.
A system remote is supplied with the A-2, the functionality of which is limited but sufficient for purpose, the only weakness is that changing level is a little crude. You have to point the handset at the amp and press the button firmly, but maybe the review sample has had more use than most. The casework is beautifully executed but has a couple of unusual elements, the vents don’t seem to be fixed firmly in and will rattle if you tap the box, this is apparently deliberate. The three feet on the A-2 are small metal studs (spikes are provided as an alternative) with two under the back corners and one right underneath the power transformer presumably to drain vibration.
Sound quality
While the evenness of tonal balance indicates that the Soulnote A-2 is a solid state amplifier, its character is very much like a push-pull tube design, which is a compliment and something that a lot of transistor amps claim to have achieved but rarely do. It has a relatively warm, rounded and relaxed presentation with superb timing and strong detail resolution for the price, but the timing is what this amp is all about and that makes it very, very easy to enjoy. Listening commenced with the A-2 driving the big Dali Epikore 11 speakers that I have managed to hang onto, at least until the next review request comes in. This is a smooth and relaxed but extremely revealing loudspeaker with wide bandwidth that’s reasonably easy to drive. The Soulnote doesn’t have the sort of grip you often get with a 100W amp but rather has a fluidity and musicality that is way more enjoyable. If you are after bone crunching bass I’d say look elsewhere, if however you’d like to feel more involved with your favourite music then read on.
It delivers excellent tonal rendering which is a typical tube characteristic, instruments sound very real and vibrant with lots of reverb and ‘air’ on acoustic examples such as Gary Burton’s vibraphone. It is also extremely nimble, there’s no sense of any overhang or blurring between notes which gives it a sense of being free of the usual electronic signature found in many transistor designs and allows the music a freedom that is inspiring. It loves vinyl as a result, great turntables also have this fluency and effortless resolution so the two work together extremely well. I’m intrigued by the Soulnote E-2 phono stage which is more expensive than this amplifier and could be rather good, these guys clearly appreciate that turntables are a fabulous source.
The balance is sweeter than your average Class AB amplifier in this price range, it makes some sound rather matter of fact but it’s a balance that suits some loudspeakers better than others. The A-2 worked well with the Dalis considering that they cost so much more and the pairing brought out all sorts of detail from well known pieces of music, these included the way that the nature of compression and recording technology leave their mark on the music. Joni Mitchell’s The Hissing of Summer Lawns (1975) sounding more like it was made in the seventies than it often does, and the track Don’t Interrupt the Sorrow flowing beautifully and seeming less complex than it can. The emphasis is very much on the music rather than its construction but that doesn’t obscure its origins. On the much more recent Kham Meslien album Fantômes… Futurs (2022) the three dimensionality of stereo makes the double bass sound very real indeed, the large instrument placed distinctly between the speakers; unforced yet tight as you like.
The bass isn’t as strong as some alternatives, it extends well and has lovely shape and fullness but isn’t as distinctly etched because the amp overall avoids the hard demarcation of leading edges. It’s a more rounded and soft bass that is perfectly timed and reflects the A-2’s ability to get out of the way and present the music with all its spirit intact. This results in a strong physical response in the listener that can occasionally result in air guitar or similar. You have been warned.
I tried the Soulnote A-2 as a power amp with a Bricasti M20 preamplifier and noted that while it doesn’t have the grip of the big Bricasti M25 (300W) it does deliver the groove in full effect. It also unearths more fine details when used this way, the preamplifier is often the limiting factor in an integrated design so when a better standalone example is introduced you get to hear what the power amp side of the equation is capable of and here it’s a lot. Transparency increases and the emotional side of the music becomes clearer as a result, I was quite carried away by Nils Frahm’s Spaces despite the obvious distortion on some tracks.
Switching back to integrated mode and hooking up PMC twenty5.26i speakers heralded a fabulous partnership that had me glued to the listening seat for many enjoyable hours. The PMCs are slightly on the lean side which proved the perfect balance for the rich A-2, the speed and tension that they found in so many pieces was thrilling. The sense of music being a live and vivid thing in the room was palpable thanks to the degree of immediacy in the sound. The sense of warm cuddliness was replaced with higher perceived transparency and tonal balance, dynamics in particular were very strong and live tracks like Ryan Adams’ Hallelujah had a depth and presence that was highly atmospheric and engaging. I even tried Seeya by Deadmau5 just to feel the drum sound and was not disappointed, in fact I was surprised to find myself listening to the whole track rather than playing the first few bars for the sound effect. The Soulnote A-2’s emphasis on the flow rather than the power of bass makes it much easier to enjoy a track like this.
Soulnote A-2 verdict
Soulnote bring big brand build and finish to products that are clearly designed by the sort of obsessive minds that are usually found behind smaller enterprises. It’s an unusual mix that on this occasion results in an amplifier that’s charming and thrilling in equal measure. While the A-2 has a limited feature set, what it does, it does extremely well for the price. You won’t find many amplifiers that are as well executed as the A-2 for the money and neither will you hear many that offer the sort of musical insights that it brings to the party. I have to say that I am very keen to hear more from Soulnote, they do things differently and the results are inspiring.