Short answer: the Topping DX5 II. Both are rated 4.9/5 (#4 and #1 of 43 DAC and headphone amp combos), and the Topping DX5 II costs $299 against $499 for the SMSL DO400, with the ratings tied, the lower price decides it.
What the SMSL DO400 does well: Audio Science Review measured 123 dB SINAD, so its noise and distortion are transparent. Watch for: It costs more than the D&A Alpha and SMSL RAW-MDA1, which share its rating and also measure transparent.
Why pick the Topping DX5 II: Audio Science Review measured a SINAD of 122 dB, so its noise and distortion are inaudible. It supports aptX Adaptive Bluetooth, which the SMSL DO400 lacks. The tradeoff: The Topping DX1 II shares its rating for well under half the price and still delivers about 1 W into 32 ohms, which is plenty for most headphones.
Buy the Topping DX5 II. Both are rated the same, and it costs $200 less than the SMSL DO400.
Looking for alternatives? See the complete Headphone Amps and DACs rankings.
Specifications Side By Side
| SMSL DO400 | Topping DX5 II | |
|---|---|---|
| Price | $499.00 | $299.00 |
| Ranked | #1 of 43 in DAC and Headphone Amp Combos | #4 of 43 in DAC and Headphone Amp Combos |
| Device Type | DAC and headphone amp | DAC and headphone amp |
| SINAD | 123 dB (measured by Audio Science Review) | 122 dB (measured by Audio Science Review) |
| Output Power (32 ohms) | 3,000 mW (manufacturer rated) | 6,400 mW (manufacturer rated, balanced) |
| Output Power (300 ohms) | 700 mW (manufacturer rated) | 990 mW (manufacturer rated, balanced) |
| Headphone Outputs | 6.35 mm, 4.4 mm balanced, 4-pin XLR balanced | 6.35 mm, 4.4 mm balanced, 4-pin XLR balanced |
| Balanced Output | Yes (4.4 mm, 4-pin XLR, XLR line out) | Yes (4.4 mm, 4-pin XLR, XLR line out) |
| Inputs | USB, optical, coaxial, AES/EBU, I2S, Bluetooth | USB, optical, coaxial, Bluetooth |
| Outputs | RCA, XLR | RCA, XLR |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, LDAC | SBC, AAC, aptX, aptX HD, aptX Adaptive, LDAC |
| DAC Chip | ES9039MSPRO | 2 x ES9039Q2M |
| Dimensions | 9.6” x 1.7” x 7.3” (245 x 42 x 186 mm) | 7.5” x 1.7” x 6.1” (190 x 44 x 155 mm) |
| Weight | 3.2 lbs (1,450 g) | 2.1 lbs (945 g) |
| Volume Control | - | Hardware knob |
| Equalizer | - | Yes (10-band parametric) |
Related Amp and DAC Comparisons
More worthwhile head-to-heads for SMSL DO400:
- D&A Alpha vs SMSL DO400
- D&A Alpha Pro vs SMSL DO400
- SMSL DO400 vs Topping G5
- SMSL DO400 vs JDS Labs Element IV
- SMSL DO400 vs Aune X1s GT
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
SMSL DO400: $499.00 Amazon eBay
Pros: Audio Science Review measured 123 dB SINAD, so its noise and distortion are transparent. A rated 3 W into 32 ohms and 700 mW into 300 ohms drives nearly any headphone, through 6.35 mm, 4.4 mm or 4-pin XLR outputs. Inputs cover USB, optical, coaxial, AES/EBU, I2S and LDAC Bluetooth, with RCA and XLR outputs for powered speakers.
Cons: It costs more than the D&A Alpha and SMSL RAW-MDA1, which share its rating and also measure transparent. At 1,450 g it is a full size desktop unit.
Full SMSL DO400 review and specifications →
| Balanced Output | Yes (4.4 mm, 4-pin XLR, XLR line out) |
|---|---|
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, LDAC |
| DAC Chip | ES9039MSPRO |
| Device Type | DAC and headphone amp |
| Dimensions | 9.6” x 1.7” x 7.3” (245 x 42 x 186 mm) |
| Headphone Outputs | 6.35 mm, 4.4 mm balanced, 4-pin XLR balanced |
| Inputs | USB, optical, coaxial, AES/EBU, I2S, Bluetooth |
| Output Power (300 ohms) | 700 mW (manufacturer rated) |
| Output Power (32 ohms) | 3,000 mW (manufacturer rated) |
| Outputs | RCA, XLR |
| SINAD | 123 dB (measured by Audio Science Review) |
| Weight | 3.2 lbs (1,450 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Topping DX5 II: $299.00 Amazon eBay
Pros: Audio Science Review measured a SINAD of 122 dB, so its noise and distortion are inaudible. A rated 6.4 W into 32 ohms and 990 mW into 300 ohms is enough for nearly any headphone, through 6.35 mm, 4.4 mm and 4 pin XLR outputs. It adds a 10 band parametric EQ, Bluetooth with LDAC and aptX Adaptive, and RCA and XLR line outputs, matching the rating of the SMSL DO400 for less.
Cons: The Topping DX1 II shares its rating for well under half the price and still delivers about 1 W into 32 ohms, which is plenty for most headphones. Its full size chassis takes more desk space than compact all in ones.
Full Topping DX5 II review and specifications →
| Released | Jun 2025 (1 year ago) |
|---|---|
| Balanced Output | Yes (4.4 mm, 4-pin XLR, XLR line out) |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, aptX Adaptive, LDAC |
| DAC Chip | 2 x ES9039Q2M |
| Device Type | DAC and headphone amp |
| Dimensions | 7.5” x 1.7” x 6.1” (190 x 44 x 155 mm) |
| Equalizer | Yes (10-band parametric) |
| Headphone Outputs | 6.35 mm, 4.4 mm balanced, 4-pin XLR balanced |
| Inputs | USB, optical, coaxial, Bluetooth |
| Output Power (300 ohms) | 990 mW (manufacturer rated, balanced) |
| Output Power (32 ohms) | 6,400 mW (manufacturer rated, balanced) |
| Outputs | RCA, XLR |
| SINAD | 122 dB (measured by Audio Science Review) |
| Volume Control | Hardware knob |
| Weight | 2.1 lbs (945 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons