Short answer: the Benchmark HPA4 if measured performance matters most, the Little Labs Monotor if price matters most. The Benchmark HPA4 ranks #13 of 19 headphone amplifiers, rated 4.0/5, at $3,499. The Little Labs Monotor ranks #14, rated 3.6/5, at $580, $2,919 cheaper.
The Benchmark HPA4 is the better-sounding option. Audio Science Review measured a SINAD of 119 dB, so the amp is transparent. Watch for: Benchmark does not publish a power figure into 32 ohms, so its output into low impedance planar magnetic headphones is unconfirmed.
Why pick the Little Labs Monotor: Audio Science Review measured a SINAD of 109 dB, clean for nearly all listening. The catch: Little Labs doesn’t publish a power figure into 32 ohms, and there are no balanced headphone outputs.
Buy the Benchmark HPA4 if measured performance is the priority over the price, or the Little Labs Monotor if the price is the priority over measured performance.
Want more options? Browse the full Headphone Amps and DACs rankings.
Specifications Side By Side
| Benchmark HPA4 | Little Labs Monotor | |
|---|---|---|
| Price | $3,499.00 | $580.00 |
| Ranked | #13 of 19 in Headphone Amplifiers | #14 of 19 in Headphone Amplifiers |
| Device Type | Headphone amp | Headphone amp |
| SINAD | 119 dB (measured by Audio Science Review) | 109 dB (measured by Audio Science Review) |
| Output Power (300 ohms) | 441 mW (calculated from manufacturer rated 11.5 Vrms into 300 ohms) | - |
| Headphone Outputs | 6.35 mm, 4-pin XLR balanced | 2 x 6.35 mm, 2 x 3.5 mm |
| Balanced Output | Yes (4-pin XLR headphone, XLR line out) | No |
| Inputs | 2 x XLR, 2 x RCA | XLR/TRS combo, TRS, 3.5 mm aux |
| Outputs | XLR, RCA | - |
| Volume Control | Hardware knob (256-step relay attenuator, IR remote) | Stepped attenuator knob |
| Dimensions | 8.7” x 3.9” x 8.3” (220 x 99 x 212 mm) | - |
| Weight | 7.9 lbs (3,600 g) | - |
Related Amp and DAC Comparisons
How Benchmark HPA4 compares with other leading options:
- Violectric HPA V550 PRO vs Benchmark HPA4
- Soncoz SGA1 vs Benchmark HPA4
- Benchmark HPA4 vs Chord Alto
- Little Labs Monotor vs Chord Alto
- Tom Christiansen Audio HPA-1 vs Little Labs Monotor
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
Benchmark HPA4: $3,499.00 Benchmark Media Systems eBay
Pros: Audio Science Review measured a SINAD of 119 dB, so the amp is transparent. It has a 4-pin XLR balanced headphone output, XLR and RCA line outputs for use as a preamp, and a 256 step relay volume control with IR remote. It is rated for 441 mW into 300 ohms, ample for high impedance headphones.
Cons: Benchmark does not publish a power figure into 32 ohms, so its output into low impedance planar magnetic headphones is unconfirmed. It costs far more than the JDS Labs Atom Amp 2, which rates higher with similar measured cleanliness. It has no built in DAC.
Full Benchmark HPA4 review and specifications →
| Balanced Output | Yes (4-pin XLR headphone, XLR line out) |
|---|---|
| Device Type | Headphone amp |
| Dimensions | 8.7” x 3.9” x 8.3” (220 x 99 x 212 mm) |
| Headphone Outputs | 6.35 mm, 4-pin XLR balanced |
| Inputs | 2 x XLR, 2 x RCA |
| Output Power (300 ohms) | 441 mW (calculated from manufacturer rated 11.5 Vrms into 300 ohms) |
| Outputs | XLR, RCA |
| SINAD | 119 dB (measured by Audio Science Review) |
| Volume Control | Hardware knob (256-step relay attenuator, IR remote) |
| Weight | 7.9 lbs (3,600 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Little Labs Monotor: $580.00 Sweetwater eBay
Pros: Audio Science Review measured a SINAD of 109 dB, clean for nearly all listening. It has two 6.35 mm and two 3.5 mm headphone outputs, XLR/TRS combo, TRS and 3.5 mm inputs, and a stepped attenuator for precise volume matching.
Cons: Little Labs doesn’t publish a power figure into 32 ohms, and there are no balanced headphone outputs. The JDS Labs Atom Amp 2 rates higher, measured cleaner and is rated at 2,650 mW into 32 ohms for far less.
Full Little Labs Monotor review and specifications →
| Balanced Output | No |
|---|---|
| Device Type | Headphone amp |
| Headphone Outputs | 2 x 6.35 mm, 2 x 3.5 mm |
| Inputs | XLR/TRS combo, TRS, 3.5 mm aux |
| SINAD | 109 dB (measured by Audio Science Review) |
| Volume Control | Stepped attenuator knob |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Little Labs Monotor vs Rupert Neve Designs RNHP
- Little Labs Monotor vs Chord Alto
- Little Labs Monotor vs Soncoz SGA1
- Little Labs Monotor vs Fosi Audio SK01
- Little Labs Monotor vs HeadAmp Gilmore Lite Mk2
- Little Labs Monotor vs Tom Christiansen Audio HPA-1
- Little Labs Monotor vs Topping A90 Discrete
- Little Labs Monotor vs Topping A70 Pro