Overview

The SMSL SU-9N is a balanced desktop DAC using ESS’s ES9038PRO. Introduced in 2021 as a lower-cost variant of the SU-9, it drops MQA/UAT while retaining high performance, USB (XMOS), optical/coaxial inputs, Bluetooth (LDAC/aptX HD/AAC/SBC), and both XLR and RCA outputs. It supports PCM up to 768 kHz/32-bit and DSD512. [2][3]

Scientific Validity

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Third-party measurements show the SU-9N reaches ≈121 dB SINAD from its balanced outputs, placing it among the top-measuring DACs on Audio Science Review. Frequency response is effectively flat, noise/distortion are well below audibility, and transparency to the source is achieved. [1]
Manufacturer data (fixed line out): XLR 4.3 Vrms / RCA 2.0 Vrms; THD+N as low as 0.000055% (A-weighted). These figures comfortably exceed audibility thresholds for electronics. [3]

Technology Level

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The design combines a flagship ES9038PRO with an XMOS XU208 USB interface and an optimized low-phase-noise clock implementation. Power is via discrete linear regulation and low-noise rails; Bluetooth supports LDAC at 24-bit/96 kHz. The approach is contemporary and competent, prioritizing measurable performance over boutique features. [2][3]

Cost-Performance

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We compare against the cheapest product that matches functions (balanced XLR, Bluetooth with LDAC, USB/optical/coax) and transparent measured performance:

• Comparator: SMSL DO100 PRO (balanced XLR/RCA, Bluetooth 5.1 with LDAC, USB/optical/coax/HDMI-ARC). Street price 219 USD. [4][6]
  Equivalence note: Same user-facing functions (incl. LDAC BT, balanced outputs) and transparent performance. For measured context, the closely related DO100 (non-PRO) has been independently tested around the ~120 dB SINAD class on balanced out, i.e., audibly transparent. [5]

CP = 219 ÷ 399 = 0.55 → 0.6 (rounded to one decimal).

Reliability & Support

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Warranty is generally 1 year on SMSL products. Implementation is retailer-centric (e.g., Parts Express PDF; SMSL web warranty/returns page). SMSL does not indicate a dedicated US repair center; forum reports on after-sales experiences are mixed, so buyers should prefer reputable sellers with clear return handling. Hardware itself is simple (few moving parts). [6][7][8]

Rationality of Design Philosophy

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Removing MQA/UAT while preserving core fidelity (very low THD+N, wide dynamic range) is a rational, measurement-first cost optimization. The feature set (balanced I/O, LDAC BT, robust USB) aligns with transparent playback requirements rather than marketing flourishes. [1][2][3]

Advice

If you want the best measurements at this price, the SU-9N delivers bona fide transparency with balanced outputs and LDAC Bluetooth. If you prioritize value with the same functions, the DO100 PRO at 219 USD undercuts it substantially while keeping LDAC and XLR; measured data for the closely related DO100 indicate transparency in practice. [4][5][6]

References

[1] Audio Science Review, “SMSL SU-9n Review (Balanced Stereo DAC)”, https://www.audiosciencereview.com/forum/index.php?threads/smsl-su-9n-review-balanced-stereo-dac.27300/ , accessed 2025-08-28. (Balanced line measurements)

[2] SMSL (official), “SU-9n product page”, https://www.smsl-audio.com/portal/product/detail/id/768.html , accessed 2025-08-28. (Functions: LDAC BT, I/O, general design notes)

[3] SMSL (official), “SU-9n Manual (PDF)”, https://www.smsl-audio.com/upload/portal/download/SU9NManual.pdf , accessed 2025-08-28. (Output levels, THD+N, feature list)

[4] HiFiGo, “SMSL DO100 PRO Dual ES9039Q2M… (product page)”, https://hifigo.com/products/smsl-do100-pro , accessed 2025-08-28. (Price 219 USD; LDAC; XLR/RCA; inputs)

[5] Audio Science Review, “SMSL DO100 Review (Stereo DAC)”, https://www.audiosciencereview.com/forum/index.php?threads/smsl-do100-review-stereo-dac.34198/ , accessed 2025-08-28. (Measured transparency on DO100)

[6] Amazon (example listing), “SMSL DO100 PRO… (Bluetooth 5.1 with LDAC)”, https://www.amazon.com/Balanced-ES9039Q2M-Bluetooth-Desktop-Decoder/dp/B0DHRXXM7P , accessed 2025-08-28. (LDAC confirmation; market availability)

[7] Parts Express, “S.M.S.L Manufacturer Warranty (PDF)”, https://www.parts-express.com/pedocs/warranty/SMSL%20Manufacturer%20Warranty.pdf , accessed 2025-08-28. (Typical 1-year warranty)

[8] Audio Science Review Forum, “What’s been your experience with SMSL/Topping reliability & warranty support?”, https://www.audiosciencereview.com/forum/index.php?threads/whats-been-your-experience-with-smsl-topping-reliability-warranty-support.32379/ , accessed 2025-08-28. (User reports on support)

(2025.8.28)