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ATC SIA2-100 integrated amplifier

ATC SIA2-100 integrated amplifier

It’s very encouraging that such masters of understatement as ATC manage to thrive in the marketing powered world of the 21st century: a testament to the increasingly challenged idea that quality will out when all around is overhyped mediocrity. ATC isn’t immune to the demands of modern audio enthusiasts but neither does it jump on every bandwagon that trundles by in the hope of making a couple of extra bucks. There are few companies in this business that have stuck to their guns so admirably and yet also appear to succeed in the marketplace through sheer bangs per buck. Compare ATC’s prices and engineering quality to almost any other company that manufacturers in the UK and you’ll see what I mean.

The SIA2-100 is the least expensive integrated amplifier that ATC offers but it generates up to 100 watts per channel of continuous power, has an onboard DAC and headphone amplifier and comes with a six-year warranty. Its design is based on a couple of other ATC components: the output stage has the same circuit as the P1 power amplifier but not the dual mono power supply found in that model. The discrete preamplifier stage was last seen in the CD2 (tested in Issue 183), which, sporting the same 2/3rds width as the SIA2-100, also featured a minijack input and full-size headphone output. The SIA2-100 has a more ‘up-to-date’ digital section based around an AKM chipset that supports PCM up to 384kHz and DSD256 via the USB input. The S/PDIF inputs don’t fly so high.

Its reduced size was a result of a demand from ATC’s Chinese distributor for a more compact design style – I like it but imagine that some may not take this amplifier seriously because it isn’t in a full width chassis. There is often a conflict between aesthetics and real-world requirements in audio equipment; electronics in particular do seem to get more traction if they have lots of bolt heads on view and substantial slabs of aluminium, plus the apparently obligatory hand biting cooling fins on either flank. Yet as this product proves, you don’t need to make something look like lab equipment for it to do a fine job. This ATC has heat sinks, but they are under vents in the top and not likely to cause any harm despite the amp’s near 10kg mass.

ATC SIA2-100 integrated amplifier, ATC SIA2-100 integrated amplifier

On the input front, the SIA2-100 is minimally but adequately equipped for most music lovers’ needs. It has two analogue inputs on RCA phonos and three digital options including coaxial S/PDIF and the aforementioned USB. ATC points out that PCs but not Macs can provide highest DSD option it supports – DSD256 – so for audiophiles at least the less fashionable platform is ultimately the most capable. It’s unusual to see a minijack input on the front of any audio component these days (USBs for thumb drives are more common), but this means that those wanting to play tunes from a smartphone can do so without the faff or sound quality limitations of Bluetooth, albeit that iPhone users are not so well catered for. This amp comes with a system remote of the practical if plain variety. It’s not fancy but it does the job more easily than the single input select button on the front panel, even though fine volume adjustments are trickier to achieve.

For reasons beyond my comprehension, I don’t have any ATC speakers to hand. Well, not totally beyond comprehension, because the last pair I had (SCM150As) were so large that I had to give them up in order to move home. So, the first speakers that fell under the SIA2-100’s command were Bowers & Wilkins 802s: substantial floorstanders with good sensitivity but a difficult load, requiring a goodly amount of power to be kept in check where the bass is concerned. I hooked up a Melco N10 music server to the USB input on the ATC and gave it a spin, which turned into a session quite rapidly, so entertaining were the results. ATC has a strong foothold in the pro audio world and its products have a sound that reflects this. I’d call it firm but fair, others might say warts and all. In essence you get a lot of detail in a very neutral fashion with no apparent ‘voicing’ involved. A few manufacturers rely on measurements alone but most tune their products to some extent, which is to say they select components that sound good to their ears in their systems. The more experienced among them do a very good job of this but few leave amplifiers sounding as lacking in apparent tuning as ATC. This means you hear both the good and the bad in any recording. Any other approach would be useless in a studio that makes acoustic recordings.

The balance is not as open as some amplifiers, but it is highly coherent and appealingly solid: you can hear an awful lot through its detail rich presentation. I enjoyed the muscularity of bass delivered by the amp through the 802s. This gives the music a solidity and drive that draws you in and gets your foot tapping. Power is clearly a strength. I doubt there are any integrateds that have as much grip at the price, and if you like to play low notes and higher levels, this is well worth having. The flip side to this is that the midrange could be sweeter, but this is something that could be balanced by a more sensible choice of speaker than the highly revealing B&Ws. ATC’s own would be the obvious choice of course; something like an SCM19 would be perfect but the SCM40 floorstander would be better still.

Abdullah Ibrahim’s piano playing never sounds soft, it has a metallic solidity to it that the SIA2-100 makes palpably clear. Keith Jarrett’s piano recordings on ECM are a lot more refined, the measured nature of his playing on Testament: London and Paris being very well presented, as was the scale of the venue, which was further defined by the low thud of his foot stomping on the stage. ATC founder Billy Woodman was a professional keyboard player back in the day and that must help. Jarrett’s playing on the Carnegie Hall Concert recording is more delicate with lovely flourishes, the instrument/venue being a little softer in character. All of this and more is easy to discern with this amplifier.

With a twenty5.26i floorstanding speaker from PMC, a company that shares ATC’s involvement in the pro side, results were once again very engaging but with a much more open perspective. This speaker works really well in my room and can sit very close to the wall, which also helps. This, combined with a relatively easy to drive load meant that the fireworks really started to kick in. Especially in imaging terms. The way it places a saxophone front and centre with real stereo solidity on Herbie Hancock’s version of ‘It Ain’t Necessarily So’ [Gershwin’s World, Verve] is inspiring. This is embellished by the rest of the band having a similar presence, underpinned by a strong bass line that keeps the groove onside and imbues the performance with a realistic verve.

ZZ Top bass player Dusty Hill sadly passed away toward the end of my listening, so I paid my respects by putting Tejas [Warner Bros] on the turntable and allowing the Rega Aphelion 2’s stylus to work its way across side A to the fabulous ‘Enjoy and Get it On’. The needle was sufficiently warmed by the third track for the raw sound of the band’s precision boogie to really get under my skin and by the time the desired track came around it was smoking, Billy Gibbons’ guitar delivering a scorching solo over the perfectly synched rhythms of Hill and drummer Frank Beard. With a digital source supplying a line level signal you get a bit more detail and finesse than the onboard DAC with equally impressive timing but in truth the result wasn’t dramatically superior to the onboard converter, and that, for a £2.5k component, is a decent result.

ATC SIA2-100 integrated amplifier, ATC SIA2-100 integrated amplifier

The ATC SIA2-100 is a remarkably well-equipped and powerful integrated amplifier that will satisfy the cravings of anyone who enjoys a bit of power behind their sound. It will drive a wide range of loudspeakers and delivers engagingly musical results while doing so. What’s not to like.



  • Type: Solid-state, two-channel integrated amplifier with built-in DAC and headphone amplifier
  • Analogue inputs: Two single-ended line-level inputs
    (via RCA jacks)
  • Digital inputs: Two S/PDIF (one coaxial, one optical), one USB port
  • Analogue outputs: One single-ended pre-out
    (via RCA jacks)
  • Supported sample rates:
  • Coaxial S/PDIF: 16-bit, 24-bit — 32kHz to 192kHz
  • USB: 16-bit, 24-bit, 32-bit — 32kHz to 384kHz
  • Input impedance: 13.8kOhms
  • Output impedance (line): 10 Ohms
  • Headphone Loads: Not specified
  • Power Output: 100Wpc @ 8 Ohms
  • Bandwidth: < 2 Hz – > 250 kHz (-3dB)
  • Distortion: 1kHz <0.0015% (-96dB), 10kHz <0.002% (-90dB)
  • Signal to Noise Ratio: Wide Band > 96dB, DIN > 108dB, > IEC “A”112dB
  • Dimensions (H×W×D): 113 × 315 × 342mm
  • Weight: 9kg
  • Price: £2,500


Manufacturer: Loudspeaker Technology Ltd. (ATC)

Tel: +44 (0)1285 760561

URL: atcloudspeakers.co.uk

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