Audio T Verdict
The ATC SIA2-100 is a compact but serious integrated amplifier for listeners who value transparency, speed and control without requiring a full-width stack of separate components.
Its discrete MOSFET Class A/B output stage produces 100W per channel into 8 ohms with both channels driven, giving it the clean power required by many high-quality standmount and medium-sized floorstanding speakers.
The built-in AKM DAC accommodates computers, CD transports, televisions and compatible streaming sources, while the analogue inputs, headphone amplifier and variable pre-output provide useful flexibility as a system develops.
There is no phono stage, network streaming or wireless connection built in. Turntables require a separate phono stage, while streaming is added through an external network player.
ATC SIA2-100 Integrated Amplifier with DAC
The ATC SIA2-100 is a compact stereo integrated amplifier combining analogue pre-amplification, a discrete MOSFET power amplifier, high-resolution digital conversion and headphone listening within one enclosure.
Its two-thirds-width cabinet occupies less equipment space than a conventional full-width amplifier while still delivering 100W per channel into 8 ohms.
ATC developed the SIA2-100 to partner its smaller and medium-sized passive loudspeakers, although it can also drive suitable speakers from other manufacturers.
100W Discrete MOSFET Amplification
The SIA2-100 uses a discrete grounded-source Class A/B MOSFET output stage based on amplification technology developed for ATC’s active loudspeakers.
ATC specifies 100W of maximum continuous output per channel into an 8-ohm load at 0.1 percent total harmonic distortion, measured with both stereo channels operating.
Stating the output with both channels driven gives a more meaningful indication of the amplifier’s ability to maintain its performance during normal stereo playback.
Wide Bandwidth and Low Distortion
The analogue amplifier section extends from below 2Hz to beyond 250kHz at the stated minus 3dB points.
This wide circuit bandwidth is intended to preserve accurate phase behaviour and clean transient response throughout the audible frequency range.
Total harmonic distortion is specified below 0.0015 percent under ATC’s stated measurement conditions, with an A-weighted signal-to-noise ratio exceeding 112dB.
Built-In AKM Digital-to-Analogue Converter
A premium AKM 32-bit DAC allows compatible digital sources to connect directly to the amplifier.
The three digital inputs accommodate a computer, CD transport, television, music streamer or another source providing a compatible digital output.
Digital input support varies by connection, so the source and cable should be chosen according to the required format and sample rate.
USB Audio Input
The rear USB Type B input is intended for direct connection to a compatible Windows, Linux or Mac computer.
It supports PCM audio up to 32-bit/384kHz. Native DSD support extends to DSD256 through a compatible Windows or Linux system and DSD128 through a compatible Mac.
USB Type B Is Not for Memory Sticks
The USB connection is a computer-audio input and is not designed for direct playback from a USB storage drive.
A suitable driver and correctly configured playback software may be required, depending on the computer and operating system.
Coaxial and Optical Digital Inputs
The coaxial S/PDIF input supports PCM audio up to 24-bit/192kHz.
The optical TOSLINK input supports PCM audio up to 24-bit/96kHz and can be useful for televisions and other sources where electrical isolation is beneficial.
The amplifier does not include an HDMI input, so television audio must be connected through a compatible optical or coaxial digital output.
Two Analogue Line Inputs
Two stereo RCA line inputs are provided for suitable analogue source components.
These can accommodate a CD player, streamer, DAC, tuner or external phono stage with a conventional line-level output.
A front-panel 3.5mm auxiliary connection provides convenient analogue access. It forms part of the amplifier’s two-input analogue arrangement rather than adding another independent pair of rear RCA inputs.
A Separate Phono Stage Is Required
A turntable cannot normally be connected directly because the SIA2-100 does not include a moving-magnet or moving-coil phono stage.
Connect the turntable to a suitable external phono stage, then connect the phono stage’s line-level output to one of the amplifier’s analogue inputs.
Discrete Headphone Amplifier
The front-panel 6.35mm headphone connection is powered by a dedicated discrete output stage rather than a simple resistor-fed speaker output.
This provides a convenient way to use compatible wired headphones without adding a separate headphone amplifier.
Headphone sensitivity and impedance vary considerably, so particularly unusual or difficult designs should be assessed through a demonstration.
Variable RCA Pre-Amplifier Output
A stereo RCA pre-output follows the amplifier’s volume control and allows an external power amplifier to be introduced as the system develops.
This means the SIA2-100 can continue to provide source selection, digital conversion and volume control while a separate amplifier supplies power to the speakers.
Suitable ATC power-amplifier options include the
ATC P1
and the more powerful
ATC P2
.
Speaker Connections
Stereo multi-way binding posts accommodate suitable terminated speaker cables.
Care should be taken when using large spade connectors or exposed bare wire because the positive and negative terminals are positioned relatively close together.
Connect or adjust speaker cables only when the amplifier is switched off, and check carefully that no loose conductor can bridge the terminals.
Remote Control and Front Display
The supplied infrared remote controls volume, input selection and other principal functions from the listening position.
The front display identifies the selected input and can be dimmed to reduce distraction in a darker room.
Normal operation does not depend on a mobile application, internet account or cloud service.
Adding Music Streaming
Network streaming is not built into the SIA2-100, but it can be added through a suitable external streamer.
A streamer with analogue outputs can connect to one of the RCA line inputs, while a model with coaxial or optical digital output can use the amplifier’s internal DAC.
Browse our range of
music streamers
for suitable options.
Matching ATC Loudspeakers
ATC specifically designed the SIA2-100 for its smaller and medium-sized passive speakers.
The compact
ATC SCM7
and
ATC SCM11
are natural partners for smaller and medium-sized listening rooms.
The larger
ATC SCM19
and
ATC SCM40
may also be considered where the room, listening distance and required volume remain suitable for the amplifier’s output.
SIA2-100 or SIA2-150?
ATC SIA2-100
- 100W per channel into 8 ohms
- Built-in high-resolution DAC
- USB, coaxial and optical inputs
- Discrete headphone amplifier
- Compact two-thirds-width cabinet
- Ideal for mixed analogue and digital systems
ATC SIA2-150
- Greater amplifier output and current capability
- Better suited to larger rooms and demanding speakers
- Full-width cabinet format
- More extensive analogue system focus
- Consider where additional dynamic headroom is required
View the ATC SIA2-150
System Matching
Well Suited To
- ATC SCM7 and SCM11 speakers
- Suitable SCM19 and SCM40 installations
- Compact high-quality stereo systems
- Computer audio through USB
- CD transports and televisions
- External music streamers
- Wired headphone listening
Check Before Buying
- No internal phono stage
- No network streaming or Bluetooth
- No HDMI connection
- Only two stereo analogue line inputs
- No balanced XLR inputs
- USB is intended for computer audio
- Speaker suitability depends on room and volume
Setup Guidance
- Connect equipment while switched off
- Check speaker-cable polarity carefully
- Prevent loose wire from bridging terminals
- Install computer drivers where required
- Begin listening with the volume low
- Leave ventilation space around the amplifier
- Use an external phono stage for a turntable
Browse our
Hi-Fi amplifiers
,
stereo speakers
,
music streamers
,
CD players and transports
,
phono stages
,
digital-to-analogue converters
and
interconnects and speaker cables
, or explore the complete
ATC range at Audio T
.
Key Features
- Compact stereo integrated amplifier with remote control
- 100W per channel into 8 ohms with both channels driven
- Discrete grounded-source MOSFET Class A/B output stage
- Premium AKM 32-bit digital-to-analogue converter
- USB Type B computer-audio input
- USB PCM support up to 32-bit/384kHz
- Native DSD256 support through compatible Windows and Linux systems
- Native DSD128 support through compatible Mac systems
- Coaxial digital input supporting PCM up to 24-bit/192kHz
- Optical digital input supporting PCM up to 24-bit/96kHz
- Two stereo RCA analogue line inputs
- Front-panel 3.5mm auxiliary analogue access
- Stereo RCA variable pre-amplifier output
- Discrete headphone amplifier with 6.35mm output
- Stereo multi-way speaker binding posts
- Front display with adjustable brightness
- Compact two-thirds-width cabinet
- Handmade in England
- Six-year ATC warranty, subject to current terms
Frequently Asked Questions
How powerful is the ATC SIA2-100?
It delivers 100W per channel into 8 ohms at 0.1 percent distortion with both stereo channels driven.
Does it include a DAC?
Yes. Its AKM DAC accepts USB, coaxial and optical digital sources, with USB PCM support up to 32-bit/384kHz.
Can a turntable connect directly?
Not normally. The amplifier does not include a phono stage, so most turntables require a suitable external moving-magnet or moving-coil phono stage.
Does it include music streaming or Bluetooth?
No. Streaming and wireless playback can be added through a compatible external network player.
Can it be connected to a television?
Yes, when the television provides a compatible optical or coaxial digital audio output. The SIA2-100 does not include HDMI.
Can an external power amplifier be added?
Yes. The variable stereo RCA pre-output allows the SIA2-100 to control a compatible external power amplifier.
Which ATC speakers are suitable partners?
The SCM7 and SCM11 are natural partners. The SCM19 and SCM40 may also be suitable depending on room size, listening distance and required volume.
How large and heavy is the amplifier?
It measures 113 x 315 x 342mm including its binding posts and weighs 9kg.
Why Buy From Audio T?
- Amplifier and loudspeaker matching advice
- Demonstrations with ATC passive speakers
- Digital-source and computer-audio setup guidance
- External streamer and CD transport matching
- Turntable and phono-stage recommendations
- Headphone compatibility advice
- Speaker-cable and interconnect guidance
- Comparison with the ATC SIA2-150
- Pre-output and future-upgrade planning
- Ongoing system setup and development support
Contact your local Audio T store
to discuss matching the ATC SIA2-100 with your speakers, digital sources, turntable and listening room.