SMSL SU-9 Review: Mid-Tier Balanced DAC

Mid-tier balanced DACs have gotten genuinely competitive in the last few years, and the DACs category is better for it. The S.M.S.L SU-9n ES9038PRO Bluetooth 5.0 DSD512 Hi-Res Balanced DAC sits squarely in that competitive middle ground, an ES9038PRO-based balanced DAC with Bluetooth LDAC and XLR outputs, aimed at buyers who want a proper desktop stack without crossing into premium territory.

The case for choosing it over competing DACs in this tier depends on a few specific factors worth laying out clearly.

What to Look For in a Mid-Tier Balanced DAC

The DAC Chip and What It Actually Tells You

The chip inside a DAC is the first thing spec-sheet buyers notice, and it does matter, but not in isolation. The ES9038PRO is ESS’s flagship Sabre chip, and published measurements of well-implemented units show a low noise floor and high SINAD. What the chip cannot tell you is how well the implementation around it performs. A well-implemented ESS chip and a mediocre one can measure very differently on ASR even at the same price band.

For mid-tier purchases, the useful signal is the full ASR measurement, SINAD, THD+N, IMD, not just the chip name on the box. Two units sharing an ES9038PRO can perform meaningfully differently depending on output stage design, power supply filtering, and board layout.

That said, the ES9038PRO at this price band is a genuinely capable starting point. The question is always execution.

Balanced Output: When It Matters and When It Doesn’t

Balanced XLR outputs are a real differentiator, in specific circumstances. If your amplifier accepts balanced input and was designed around it, balanced output from a DAC typically improves noise rejection, particularly in longer cable runs or environments with interference. For a desktop stack where DAC and amp sit inches apart, the practical noise benefit is modest.

Where balanced output meaningfully matters is in the signal chain: a DAC with proper differential balanced outputs will typically measure better at the output stage than the same DAC’s single-ended output. The ES9038PRO’s architecture supports this well. If the amplifier receiving the signal is also balanced-capable, Topping L50 and several others in this tier, the case for using XLR over RCA is real.

Balanced connections also eliminate ground loop hum more reliably than RCA in complex desktop setups. For most listeners running two boxes on a desktop, it remains a meaningful but secondary consideration rather than a primary reason to choose one DAC over another.

Bluetooth LDAC: Legitimate Convenience, Bounded Ceiling

LDAC Bluetooth at 990 kbps is meaningfully better than SBC or AAC. LDAC is intended to be close enough to a wired connection for casual listening that background sessions don’t require the cable.

The ceiling matters, though. Bluetooth LDAC is still a lossy compressed codec. USB input generally provides cleaner measured performance than Bluetooth input, regardless of codec. For critical listening sessions, the wired input remains the right choice. LDAC is a convenience feature that works well for its use case, background listening, phone sources, casual sessions, not a replacement for a clean USB signal from a dedicated source.

Remote Control and UI Usability

Desktop DACs that require physical front-panel navigation for input switching become friction points over time.

For a DAC used primarily in fixed-input mode feeding a dedicated amp, the remote matters less. For users who switch regularly between USB, optical, and Bluetooth sources, reliable remote control is a genuine quality-of-life factor. Worth factoring into your comparison if source-switching is part of your workflow.

Exploring the full range of balanced DAC options before committing to a chip tier is worth the time, remote and interface usability differences that seem minor in spec comparisons accumulate in daily use.

Top Picks

S.M.S.L SU-9n ES9038PRO Bluetooth 5.0 DSD512 Hi-Res Balanced DAC

The S.M.S.L SU-9n is the kind of product that makes the mid-tier DAC market genuinely interesting. It is an ES9038PRO-based balanced DAC with XLR outputs and Bluetooth LDAC; check published measurements for its SINAD and noise floor before buying.

A remote is included, which helps if you regularly switch between USB and Bluetooth input.

The SU-9n’s appeal is pairing balanced XLR outputs with Bluetooth LDAC.

For listeners running a balanced amp, such as the Topping L50, and wanting Bluetooth convenience without downgrading the measurement floor, the SU-9n makes a strong argument. Topping offers competing DACs in this tier. The decision, for most buyers, comes down to whether LDAC convenience is a priority and whether brand ecosystem consistency (full SMSL stack versus mixing) matters to you. Neither answer is wrong.

Check current price on Amazon.

Buying Guide

Balanced vs. Single-Ended: Choosing the Right Output Type

The most consequential decision before buying in this tier is whether your amplifier supports balanced input. A balanced DAC paired with a single-ended amplifier outputs via RCA, the XLR capability is irrelevant in that configuration. Verify your amplifier’s input options before treating balanced output as a purchase justification.

If your amp is balanced-capable, the case for a balanced DAC strengthens considerably. Properly implemented balanced outputs provide better noise rejection and typically measure cleaner than the same unit’s RCA stage. At this tier, that measurable difference is real even if it sits below the audibility threshold for most listeners on most tracks.

ES9038PRO vs. AKM vs. R2R: Understanding the Chip Landscape

ES9038PRO is an ESS Sabre flagship chip. AKM chips in the same tier and R2R ladder DACs use different architectures; R2R designs are generally found at higher price points for equivalent measured performance.

For most buyers at the mid-tier, the chip preference question is secondary to implementation quality and output stage design. Published measurement databases are the right tool here: look at the full measurement suite for specific units, not just the chip tier.

For daily listening, the implementation matters more than the chip family.

USB vs. Bluetooth: Matching Input to Use Case

USB input from a dedicated source, a computer with a clean USB output, or a USB reclocker, provides the cleanest measured signal path through any DAC in this tier. If your primary source is a desktop or laptop and critical listening is the priority, USB is the correct input choice.

Bluetooth LDAC is a meaningful upgrade over earlier codecs and performs well for casual listening and phone-source sessions. The practical question is whether you need both, and the SU-9n’s value proposition is specifically that you get both without compromise in either direction.

Buyers who would never use Bluetooth don’t need to pay for it. For USB-only use, Topping’s DACs in this tier are worth including on a comparison shortlist.

Sensitivity Matching: DAC Output Voltage and Amplifier Input

Output voltage matters more than most mid-tier buyers realize. The SU-9n’s balanced output reaches 4Vrms, a level that can overdrive the input of some integrated amplifiers not designed for DAC-level signal. Verify your amplifier’s maximum input sensitivity before pairing.

For dedicated headphone amplifiers designed around DAC pairing, which is the dominant use case at this tier, 4Vrms balanced is appropriate and expected. For buyers integrating a DAC into a speaker-based system with a receiver or integrated amp, check the manual.

Long-Term Ownership and Firmware

Firmware updates for DACs in this tier are infrequent in general; the unit is unlikely to require them for core functionality.