Questyle SIGMA Pro — Decision Profile
L2 Decision Profile · documentation + editorial assessment
Quick verdict
A portable DAC/headphone amp and line/recording interface when output mode is carefully matched
Avoid if: Direct passive-speaker drive, raw-cartridge phono gain or Studio mode for sensitive IEMs
Evidence checked: 2026-10-17. Manufacturer documentation; no independent SoundPath Lab listening, measurement, compatibility or firmware retest.
System conditions
Select IEM/HP/LINE before connecting, use low initial volume and a proper5 V/2A charger; match analogue input1 V SE/2 V BAL. Windows native DSD may require the maker driver
Documented specifications
| Item | Specification and conditions |
|---|---|
| Routes | USB-C UAC2, optical/coaxial and Bluetooth inputs; 3.5/4.4 mm analogue inputs; 3.5/6.35 mm SE and 4.4 mm balanced outputs |
| Digital limits | USB PCM 768/32/native DSD512; optical/coax PCM 192/24; driver/DoP conditions apply |
| Power condition | Manual: >1200 mW at 32 ohm balanced; pre-out3.3 V SE/6.6 V BAL at 300 ohm |
| Power/recording | Separate USB-C 5 V/2A charge and USB audio ports; analogue inputs support USB recording |
| Mode conditions | IEM/HP/LINE modes; Studio high-voltage gain must not be used with Hi-Fi IEMs |
Limits and source qualifications
Loaded power/noise, recording performance, battery runtime and Bluetooth interoperability were not measured by SPL
- The manufacturer-authored quick guide is read through an indexed mirror; the spec page uses legacy RCA/XLR labels despite jack outputs. No physical RCA/XLR sockets are inferred
Alternatives by need
X18 is a desktop line DAC without accepted headphone drive; NHB15 is an integrated USB-C earphone, and a QCC dongle transmits rather than receives Bluetooth
Keep or upgrade
Keep a working system that already meets these requirements. Consider a change only when the documented connection, control or system role solves a specific unmet need; no measured sound-quality upgrade is claimed.
Evidence, support and reassessment
Review scope
Exact-model primary specification and connection sections cited below were reviewed. Source claims and editorial system-fit reasoning are distinct from independent listening, measurement, compatibility or firmware tests; none were added.
Actual sound, under-load output, room/ear fit, latency and long-term reliability remain untested. Existing scores, Builder qualification and owner/test records were not reassessed.
Firmware and regional support
Local stock, authorized sales, transaction prices and long-term support duration are not established by this documentation review. Dated regional announcements apply only to their stated territory and terms. Existing dated price and owner evidence is retained.
No installed firmware version or issue resolution was retested. Follow the exact-model official support workflow.
Reassess when evidence changes
Reassess on verified hardware or firmware changes, clarification of a source conflict, material support/compatibility changes, or accepted independent testing.
No new six-month ownership evidence was added; existing owner and issue records remain unchanged.
Related records and tools
- Gustard DAC-X18
- Questyle NHB15
- Product directory
- System Builder
- Issues and limitations
- Firmware and app tracker
- Compare this product
Sources checked
- Official model material
- Manufacturer-authored document — independently hosted mirror; relevant sections reviewed
Revision: 2026-10-17 — L0/L1 to L2 after model-level documentation and decision review. Product identity and existing scores/qualification retained. L2 is evidence coverage, not independent test acceptance.
Member knowledge · editor reviewed
Questions, owner experience and product issues
Join the live member discussion below, or submit structured experience and issue reports for editorial review.
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