Short answer: the SMSL D400 Pro. Both are rated 4.8/5 (#10 and #8 of 30 DACs), and the SMSL D400 Pro costs $728.20 against $749 for the Gustard X18, and with measured performance even, the cheaper one is the better buy.
Why pick the Gustard X18: Audio Science Review measured a SINAD of 122 dB, so its noise and distortion are inaudible. Watch for: The Topping D70 Pro SABRE matches its rating and measured slightly cleaner for less, and the SMSL D-6S matches its rating for a fraction of the price.
The case for the SMSL D400 Pro: Audio Science Review measured 122 dB SINAD, so its noise and distortion are inaudible. Watch for: It is a DAC only, so you need a separate headphone amp or powered speakers.
Buy the SMSL D400 Pro. Both are rated the same, and it costs $20.80 less than the Gustard X18.
Looking for alternatives? See the complete Headphone Amps and DACs rankings.
Specifications Side By Side
| Gustard X18 | SMSL D400 Pro | |
|---|---|---|
| Price | $749.00 | $728.20 |
| Ranked | #8 of 30 in DACs | #10 of 30 in DACs |
| Device Type | DAC | DAC |
| SINAD | 122 dB (measured by Audio Science Review) | 122 dB (measured by Audio Science Review) |
| Balanced Output | Yes (XLR line out) | Yes (XLR line out) |
| Inputs | USB-B, I2S (HDMI), AES/EBU, coaxial, optical, Bluetooth | USB, optical, coaxial, I2S, AES, Bluetooth |
| Outputs | RCA, XLR | RCA, XLR |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, aptX LL, LDAC | SBC, AAC, aptX, aptX HD, LDAC |
| DAC Chip | ES9038PRO | AK4499EX + AK4191EQ |
| Volume Control | Hardware knob | - |
| Dimensions | 8.7” x 2” x 6.7” (220 x 50 x 170 mm) | 10” x 1.8” x 7.4” (254 x 46 x 189 mm) |
| Weight | - | 4.2 lbs (1.9 kg) |
Related Amp and DAC Comparisons
How Gustard X18 compares with other leading options:
- Gustard X18 vs SMSL SU-10
- Gustard X18 vs SMSL RAW Pro-DAC1
- Gustard X18 vs SMSL VMV D1se2
- Gustard X18 vs Topping D70 Pro SABRE
- Gustard X18 vs Topping D90 III Sabre
Prices on this page were last checked October 11, 2026 at 4:59 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Amps and DACs In Full
Gustard X18: $749.00 Amazon eBay
Pros: Audio Science Review measured a SINAD of 122 dB, so its noise and distortion are inaudible. It has nearly every input you could want, including USB, I2S over HDMI, AES/EBU, coaxial, optical and Bluetooth with LDAC and aptX HD. It feeds an amp or powered speakers through RCA or balanced XLR outputs, with a volume knob for direct control.
Cons: The Topping D70 Pro SABRE matches its rating and measured slightly cleaner for less, and the SMSL D-6S matches its rating for a fraction of the price. Its full width chassis takes up more desk space than compact DACs.
Full Gustard X18 review and specifications →
| Released | Dec 2021 (4 years ago) |
|---|---|
| Balanced Output | Yes (XLR line out) |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, aptX LL, LDAC |
| DAC Chip | ES9038PRO |
| Device Type | DAC |
| Dimensions | 8.7” x 2” x 6.7” (220 x 50 x 170 mm) |
| Inputs | USB-B, I2S (HDMI), AES/EBU, coaxial, optical, Bluetooth |
| Outputs | RCA, XLR |
| SINAD | 122 dB (measured by Audio Science Review) |
| Volume Control | Hardware knob |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
SMSL D400 Pro: $728.20 HiFiGo eBay
Pros: Audio Science Review measured 122 dB SINAD, so its noise and distortion are inaudible. It has a wide range of inputs, including USB, optical, coaxial, I2S, AES and Bluetooth with LDAC, aptX HD, aptX, AAC and SBC, and outputs to amps or powered speakers over RCA or balanced XLR.
Cons: It is a DAC only, so you need a separate headphone amp or powered speakers. The Topping D70 Pro SABRE earns the same rating and measured slightly cleaner for less, and the SMSL DO200 Pro matches its SINAD for much less. No volume control is listed, so it may not work as a preamp for active speakers.
Full SMSL D400 Pro review and specifications →
| Balanced Output | Yes (XLR line out) |
|---|---|
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, LDAC |
| DAC Chip | AK4499EX + AK4191EQ |
| Device Type | DAC |
| Dimensions | 10” x 1.8” x 7.4” (254 x 46 x 189 mm) |
| Inputs | USB, optical, coaxial, I2S, AES, Bluetooth |
| Outputs | RCA, XLR |
| SINAD | 122 dB (measured by Audio Science Review) |
| Weight | 4.2 lbs (1.9 kg) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons