Initial conversations with ATC (Acoustic Transducer Company) were centred around their stunning speaker reputation but the opportunity to listen to their electronics was too hard to turn down especially when paired with a complimentary CD player. The ATC SIA2-100 and matching CD2 are the compact siblings to the physically larger SIA-150 and CDA2 that are part of the ATC electronics range that includes pre and power amplifiers, monoblocks and active loudspeaker solutions for ATC speakers.
ATC SIA2-100 Design
The SIA2-100 is a compact Stereo Integrated Amplifier (SIA) with a claimed 100W per channel into 8 Ohms, it uses a discrete MOSFET transducer configuration which helps with amplification efficiency, improving sound output. It is functional in input terms with two line level inputs and three digital inputs as well as a 3.5mm input jack on the front panel which is interesting. It features an AKM 32-bit DAC making this integrated amplifier a very competent and flexible option on the digital side where many amplifiers concentrate on the analogue function.
The ATC SIA2-100 dimensions are 113 x 315 x 342mm (H x W x D inc. binding posts), it weighs in at 9kg.
ATC CD2 Design
The CD2 is the perfect partner to the ATC SIA2-100 in size and complementary function. It has both balanced XLR and unbalanced RCA outputs. The XLR output is strange because the integrated amplifier does not have XLR inputs, so the CD player takes up one of the line level inputs on the SIA2-100, unless you go for a digital connection of course.
There are no digital inputs to take advantage of the clearly excellent AKM 32-bit DAC with this CD2 though the same DAC is in the SIA2-100. There are, however, both optical and coaxial digital outputs leaving the TEAC CD Transport in charge of data collection if you choose this option. Overall, the CD functionality comes across as well thought out. There is a remote control with the CD player that is a little bit of a disappointment as it is quite plasticky with rubber buttons, but there we are.
The CD2 dimensions are 77 x 315 x 327mm (HxWxD inc. chassis connectors) and it is 3.85kg.
The SIA2-100 retails at £2,500 and the CD2 is £1,750.
Both the CD2 and SIA have a lovely touch and are a perfect match. The main casework is metal and has a patterned fan-shaped top to release heat. The front panel appears to be a brushed aluminium finish and it is very aesthetic. I really appreciate the uncluttered look in the SIA and the CD2 is similarly minimalist with a matching blue LED information display showing input selection on the SIA and the usual track detail on the CD2 LED.
The compact design style makes this combination a fine-looking stack of electronics on the test bench.
Review Equipment and CDs
I’m listening to the ATC SIA2-100 System with both a Bluesound Node (2021) and separately a newly arrived Auralic Altair 2.1, both digital out to hear the SIAs DAC. Mainly I’m using the CD2 though with the familiar Kudos Cardea C10s with Tellurium Q Black II speaker cable though I have switched speakers to the PMC Twenty5 26is which are gorgeous towards the end of the review.
Fortunately for me, Radiohead has just released a 20 year old celebration of their Kid A/Amnesiac recordings called Kid A Mnesia, and I have it on CD. As a firm fan of Amnesiac, I am delighted to be reviewing a CD based system at this time. Otherwise, it seems appropriate to select my other favourite CDs for review purposes, notably; Automatic for the People, Helplessness Blues, Led Zeppelin II, The Next Day, Undercurrent by Bill Evans and Lana Del Rey’s Chemtrails over the Country Club.
The system is a joy, I have the SIA on top of the CD player as that’s how it is in the ATC pictures, and I feel the weight of the amplifier will stabilise the CD mechanism. The amplifier does not run particularly hot, and the CD is s cool as a cucumber.
The remote control, despite being a bit plasticky, is really responsive and the volume control is exceptionally rapid. You can dim the display using the remote which is useful where I thought it was a bit bright.
As for the CD itself, the mechanism is very quiet indeed and track selection is very accessible with the remote or the simple layout on the front panel.
this is a muscular, powerful, and engaging soundstage delivered by the SIA2-100
As a system, this is a very pleasurable experience indeed, this is a muscular, powerful, and engaging soundstage delivered by the SIA. I do know ATC loudspeakers are not unlike these Kudos speakers in that they have a high impedance and therefore benefit from a more powerful amplifier which the SIA2 is into 8 Ohms. There is plenty of power in the room with this SIA design and the Kudos C10s are singing.
The CD2 player
…and yet I’m wondering to myself if the CD player isn’t sounding at least as good as the Qobuz 24-bit, 96kHz version
I’ve been back into CDs after the Exposure review, which I did at the start of the year, I do connect with the process of order (alphabetical of course!), selection, placement, and then musical engagement. The ATC CD2 is a coherent and musical CD player, meaning it gives a clear and resolved analogue signal that appears to me to leave very little behind. For example, R.E.Ms Automatic for the People opener Drive is delivered with a precision that is matched only by the Altair G2.1 streaming DAC and yet I’m wondering to myself if the CD player isn’t sounding at least as good as the Qobuz 24-bit, 96kHz version. It could well be that it is better; how can this be if I have more information coming from a 24-bit version?
I wanted to try the CD2 on its own with my Moor Amps pre and power combination. In this case with the additional grip offered by the Angel 6 power amplifier, the wide and clean guitars in Drive and Find the River are just perfectly delivered by the CD2 and the Kudos C10s.
there is flexibility and fidelity here combined with a ton of muscle to raise this system above most in this competitive space
As a DAC, I’m thinking this off the shelf AKM (Asahi Kasei Microdevices) 32-bit DAC is really a rather special bit of kit and it certainly feels as if it translates the Bluesound Node (2021) signal very effectively through a Chord Cables’ Coaxial feed. I’m feeding the digital signal into the ATC SIA2-100, the same chip is in the CD player that is converting the CD signal to analogue. I guess you could take a digital signal from the CD player into the ATC SIA2-100 but I have not done this.
The issue at hand here is the SIA2-100 and the CD2 are effectively an all in one HiFi solution (retailing combined near £4,250) and thus are competing in a very competitive space, dominated by the likes of Naim (Uniti Star, £3599 or Nova, £4299), Moon (ACE, £3300) and NAD (M33, £3999), although we should note there is no onboard streaming solution here. Having said that, there is flexibility and fidelity here combined with a ton of muscle to raise this system above most in this competitive space. Additionally, here we have a system around which you can build your HiFi journey should you wish to explore high-end turntables, headphone amplifiers or HiRes streaming solutions.
Headphone output from the SIA2
The 6.35mm headphone output at the front is perfectly acceptable and I have no complaints listening with the T+A Solitaire P-SE. The headphone being used cuts the speaker output which is helpful.
This ATC SIA2-100 in combination with the ATC CD2 is a fine and muscular system. There is plenty of power here to drive the most demanding of speakers. I have thoroughly enjoyed the flexibility and fidelity of the SIA2 and the AKM DAC is a real winner. This is a lifetime HiFi solution around which you can confidently build and add to as your musical journey progresses. This is a very well thought out system.
AKM 32-bit DAC
Balanced inputs on the SIA2
The remote was more Zen
Streaming solution to make it an all in one system