EARMEN ST-AMP DAC/headphone amp/preamp
+ Neutral-bright and exciting sound signature; balanced analogue input and preamp output options; compact footprint; fully balanced design; quiet amp section.
– Struggles with busy passages; awkward volume curve; no gain switch; old-school style USB-B connection.
A guide to the ratings
DESKTOP headphone enthusiasts have a plethora of options when it comes to compact USB DAC/amps. For those of us with limited desk space, mid-sized separates like the Schiit Modius DAC + Magnius amp are not an option, which is why the iFi Zen stacks and other compact solutions are so popular. Even something as compact as the Hifiman EF400 would still be too big for some people once you take into account a computer and additional desk space for books.
The EarMen ST-Amp is a solid contender in this space. Measuring 170 x 30 x 150mm and weighing 1.1kg, it is small but heavy due to the linear power supply and chassis. It comes with no accessories except for the unit itself and a user manual booklet. While it has three feet instead of four, the ST-Amp’s design is simple and straightforward, with a large volume control taking centre stage in front, flanked by toggle switches for power and input control, and 4.4mm balanced and quarter-inch unbalanced headphone outs.
On the rear, the ST-Amp features RCA inputs and outputs for single-ended connections and 4.4mm input and output for balanced connections. There’s also a USB-B connector for the digital input, which may be a disappointment for some users who prefer the more modern USB-C or micro USB.
The ST-Amp uses two Texas Instruments TPA6120 chips for the analogue output, the same ones found in EarMen’s portable TR-Amp DAC/Amp, but instead of one, two chips are used for the unit’s balanced analogue output. The ST-Amp also features an ESS ES9280 DAC chip, the same one found in the EarMen Eagle, which supports DSD over PCM (DoP) 64/128, DXD 384/352.5 kHz, and PCM up to 384kHz. It has a very low 0.002% THD and a high signal-to-noise ratio (SNR) of +125dB from the balanced output.
While the ST-Amp’s internals are recycled from EarMen’s lower-end products, and its compact form factor seems to be geared towards budding audiophiles, the U$599 price tag suggests otherwise. So how does it sound?
The ST-Amp’s output is clean and reminded me of the TR-Amp. It also has the same volume curve as the TR-Amp, with the volume progressively increasing up to 10 o’clock, followed by a small volume increase up to the 2-o’clock position; it continues to progressively increase all the way, almost like an “S” curve.
For albums mastered without dynamic compression (don’t you just love the loudness war?), such as Anne Bisson’s Blue Mind and Vanessa Hernandez’s Use Me, I had to turn up the volume three-quarters of the way to fully appreciate the vocals. However, with my sensitive Final Audio Pandora Hope VI headphones, I enjoyed the ethereal flow of Bisson’s vocals and all the cracks in her voice.
Sophie Zelmani’s All About You from her 2011 album Soul was just liquid gold to my ears. Her breathy, almost whispering voice was portrayed transparently, and I could hear the distinct snares when the drum hit, which decayed softly with the shimmering reverb from post-processing.
The ST-Amp lags a little when it tries to resolve complex passages, as demonstrated in Bradley Cooper’s Black Eyes from the A Star Is Born soundtrack. This affects imaging in a way that makes it fuzzier, but there’s some extra energy injected into the track by the unit that made me want to rock it out on speakers instead. Tapping toes and bobbing heads? I gotta admit that’s not half bad!
I made a U-turn from loud rock music and dug out The Stranger by Allan Taylor. His album Hotels & Dreamers is such a classic to me. The ST-Amp managed to dig down in the lower octaves to reproduce his deep voice. Imaging in this case was spot on, and I could pick out both guitars effortlessly.
For pop music lovers, they might appreciate the brightness and energy the ST-Amp has. There’s however a trade-off with the bass. It doesn’t punch as hard as I’d like with Dua Lipa’s Levitating track. The track itself doesn’t go so deep that it rumbles through your headphones, but the drum lines are punchy enough to reveal the amp’s sound signature.
Balanced vs single-ended
After listening to Maria Maria by Santana featuring The Product G&B from my Ultimate Santana CD (88697 15502 2, Arista) multiple times, I was initially puzzled by the return of the punchy bass. It wasn’t until I realised that I had switched to a balanced cable that the mystery was solved.
Not only did it provide an increase in volume, but it also gained more control over the low end due to the extra power swing from the 4.4mm output. If you’re a balanced user, I highly recommend using this cable as your main. However, it’s important to note that if you plug both headphone outputs, the ST-Amp will automatically mute the 4.4mm connection and prioritise the quarter-inch output.
THE LAST WORD
Overall, the ST-Amp performs well as an entry-level headphone DAC/amp, though at the price, it would have been appreciated if EarMen had provided a gain switch, as some users may need to turn up the volume on half of their music library. The unit’s build quality is excellent, and the choice of inputs and outputs allows for future expansion and equipment upgrades.
While the ST-Amp may not be perfect, it offers solid performance and quality albeit at a higher price point. However, it merits consideration for those looking to dip their toes into the world of headphone DAC/amps.
Sources: Mac Mini M1 / Headphones: Sennheiser HD525, HD650, Final Audio Pandora Hope VI, JVC HA-S500 / DACs: Chord Hugo V1, Matrix Mini-i, Aune T1
Review sample courtesy of Auris Audio / Find your distributor.