SMSL SU-2: New Sub-$100 DAC Brings XLR Output

The SMSL SU-2 is the first desktop DAC to feature balanced XLR output for under US$100. However, this comes at the cost of removing the USB port, a digital connection that is widely used in many scenarios. Check out the features and specifications of the SU-2 and see whether it will suit your needs.

What are the differences between the SMSL SU-2 and the SU-1?

The main differences between the SMSL SU-2 and the SU-1 are:

• Absence of a USB input
• Balanced XLR connection
• Power supply with a C14 connector

The USB-C input on the SMSL SU-1 is one of the most commonly used connections on both desktop and portable DACs. For some reason, SMSL decided to remove this digital connection on the SU-2 and replace it with AES/EBU.

Balanced XLR output was previously nonexistent in desktop DACs under US$100, so it was a surprise to see that the SMSL SU-2 includes this connection. This makes it possible to connect the DAC to desktop amplifiers that feature balanced XLR inputs, which usually provide higher voltage compared to RCA, improving pre-amplification performance.

According to the DAC’s specifications, the XLR outputs on the SU-2 are truly balanced and are not included merely for convenience.

Using a C14 connector on the SU-2 has the advantage of providing a ground pin, which helps prevent noise. In addition, this connector offers a firmer fit and is more robust compared to USB-C.

Which DAC chip is used in the SMSL SU-2?

The SMSL SU-2 uses the ESS ES9039Q2M DAC chip. This DAC from the “SABRE” series was launched in March 2023 and offers “2 channels of ultra-low noise digital conversion, with a dynamic range (DNR) of +130 dB and THD+N of −120 dB per channel,” according to the manufacturer.

What is used for pre-amplification in the SMSL SU-2?

SMSL chose to use four OPA1612A operational amplifiers (op-amps) from Texas Instruments (TI) in the SU-2, which are “arranged in a symmetrical architecture within the DAC and analog amplification sections,” according to the manufacturer.

According to the SU-2’s developer, “this design does not merely stack components; instead, it creates a signal path with low distortion and a high common-mode rejection ratio through precise matching and independent adjustments.” The company adds:

“The goal is to systematically minimize crosstalk and noise at every stage, ultimately achieving high-fidelity linear amplification of signals across a wide bandwidth, ensuring that dynamic and subtle audio details are preserved.”

SMSL SU-2 – Specifications

Inputs: AES / Optical / Coaxial

Output level:

• XLR: 4.7 Vrms
• RCA: 2.3 Vrms

THD+N (Total Harmonic Distortion + Noise):

• XLR: 0.00006% (−123.5 dB)
• RCA: 0.00008% (−121.5 dB)

Dynamic range:

• XLR: 130 dB
• RCA: 126 dB

SNR (Signal-to-Noise Ratio):

• XLR: 130 dB
• RCA: 126 dB

Bit depth on Optical / Coaxial / AES inputs: 16-bit ~ 24-bit / 1-bit

Sampling rate on Optical / Coaxial / AES inputs:

• PCM: 44.1 kHz ~ 192 kHz
• DSD: DSD (64 DoP)

Power consumption: < 2.3 W

Standby power consumption: < 0.1 W

Dimensions: 15 cm × 4.2 cm × 13.3 cm

Weight: 532.6 g

Launch, price, and availability

The SMSL SU-2 is already available for purchase at US$99.99 on AliExpress.