SMSL SU-9 Review: Mid-Tier Balanced DAC Tested

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.

Owner consensus and ASR measurements put it in a strong position. The case for choosing it over the Topping E50 , or against it , 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. ES9038PRO has a strong reputation, and for good reason: verified measurements across multiple ASR entries show low noise floor, excellent SINAD, and channel separation that holds up in balanced operation. 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. Owner reports and community measurement threads are the right reference here, not the marketing tier of the silicon.

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, SMSL SH-9, 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. Verified buyer reports on the SU-9n note that LDAC connection is reliable and that the sound quality difference versus USB is small enough that casual listening sessions don’t require reaching for the cable. That’s a reasonable read of what LDAC can deliver.

The ceiling matters, though. Bluetooth LDAC is still a lossy compressed codec. ASR’s general position , and the consensus across Head-Fi threads covering this DAC , is that USB input 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.

The SU-9n’s LDAC implementation has drawn generally positive owner feedback. Dropouts are infrequent under normal desktop conditions. That’s worth more than the codec spec alone.

Remote Control and UI Usability

This one rarely appears in measurement reviews, but it shows up consistently in long-term owner reports. Desktop DACs that require physical front-panel navigation for input switching become friction points over time. The SU-9n includes a remote, and owner consensus is that it functions reliably for input selection and volume (when the internal volume control is in use).

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. ES9038PRO implementation, balanced XLR outputs, LDAC Bluetooth, and a price band that puts it directly against the Topping E50 , a unit I run daily on my own stack. ASR’s measurements on the SU-9n are competitive: SINAD in the range that satisfies any technically-oriented buyer, noise floor well below audibility, and balanced output performance that validates the XLR option as more than cosmetic.

Owner feedback is consistently positive on the build quality , SMSL’s metal chassis feels appropriately solid at this tier , and on the Bluetooth reliability. LDAC pairing with Android sources draws favorable reports, with few complaints about dropouts under typical desktop conditions. The remote functions as advertised, which matters more than it sounds if you regularly switch between USB and Bluetooth input.

Where the comparison with Topping E50 gets honest: the E50 is my reference at this tier, and the honest position is that both units perform at a level where the audible difference on well-matched amplification is extremely small. The SU-9n’s edge is Bluetooth LDAC, which the E50 lacks, and its balanced input stage is well-executed. Planar magnetic headphones , the Sundara specifically , showed me that the “scales with source” argument I’d written off had real content. Swapping sources produced small but real differences I hadn’t expected. The SU-9n holds up on that front.

For listeners running a balanced amp , Topping L50, SMSL SH-9, or similar , and wanting Bluetooth convenience without downgrading the measurement floor, the SU-9n makes a strong argument. The competition from Topping is real. 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.

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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 with a distinctive sonic profile that some listeners describe as analytical. AKM chips in the same tier tend toward a warmer, slightly rolled character. R2R ladder DACs operate on a different architecture entirely and 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. ASR’s database is the right tool here: look at the full measurement suite for specific units, not just the chip tier. The SU-9n’s ES9038PRO implementation scores well on that benchmark.

Community consensus on Head-Fi and the dedicated DAC forums supports the position that chip differences are audible primarily in A/B comparisons under controlled conditions. 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 SU-9n’s implementation is stable and reliable by owner consensus. 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. The Topping E50 remains the benchmark competitor in this tier for USB-only use cases and should be on any 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

SMSL’s update history on this unit has been quiet, which is either a sign of a stable, finished product or limited ongoing support , owner reports suggest the former. Firmware updates for DACs in this tier are infrequent in general; the unit is unlikely to require them for core functionality.

The remote and LDAC reliability are the most-cited long-term satisfaction factors across owner reviews. Both hold up well in reports from users twelve or more months in.

Frequently Asked Questions

How does the SMSL SU-9n compare to the Topping E50?

Both units are ES9038PRO-based and measure competitively on ASR. The primary differentiator is Bluetooth LDAC , the SU-9n includes it, the E50 does not. The E50 is often cited as the cleaner-measuring unit on USB input in direct comparisons, though the audible gap is small. Buyers who want wireless source capability have a clear reason to choose the S.M.S.L SU-9n; buyers running USB-only can treat both as equivalent and compare on price and build preference.

Does the SU-9n require a balanced amplifier to sound its best?

No, but a balanced amplifier unlocks the DAC’s measured performance advantage. Running XLR out into a balanced-input amp produces better noise floor and separation than the RCA output in most implementations. If your amplifier is single-ended only, the SU-9n still performs well via RCA , the XLR outputs are simply unused capacity.

Is LDAC Bluetooth actually worth using on a desktop DAC?

For casual listening and phone sources, owner consensus is yes. LDAC at 990 kbps provides meaningfully better wireless audio quality than SBC or AAC, and the SU-9n’s implementation is stable and reliable. For critical listening sessions, USB remains the better input. The value of LDAC on a desktop DAC is convenience , quick phone source switching without cable handling , not a replacement for wired signal quality.

What amplifiers pair well with the SU-9n?

Balanced amplifiers designed for DAC pairing , Topping L50, SMSL SH-9, and similar mid-tier units , are the natural match. These accept 4Vrms balanced input without overloading and present a clean load to the DAC’s output stage. Single-ended pairing with a quality RCA-input amp works well too; the Schiit Magni line is frequently cited alongside this DAC in Head-Fi stack threads.

Does the SU-9n support MQA decoding?

The SU-9n does not include MQA hardware decoding. For listeners using Tidal who encounter MQA streams, software unfolding via the streaming app will pass a decoded PCM signal to the DAC. Full MQA hardware rendering is absent, which aligns with the general direction of the mid-tier DAC market , and with ASR’s consistent position that MQA’s audible benefits over high-resolution PCM are not reliably demonstrable.