Outboard DACs

I tasked the ST-Amp's balanced output with a pair of Meze Audio 109 PROs which, despite the name, isn't a neutral studio headphone but an over-ear, open-backed dynamic driver design that affords a slightly mellow listen. Furthermore, with its rated 112dB sensitivity and 40ohm impedance, the 109 PRO did not force the ST-Amp to break sweat. I didn't need to turn the volume dial very far to get an agreeable level, and to discover how the amp was delivering the fluid playing of violinist Merel Vercammen on The Zoo [TRPTK TTK0042; 88.2kHz/24-bit].

This early recording from the upstart Amsterdam label demonstrates engineer Brendon Heist's knack for capturing astonishing levels of detail and texture, which may have something to do with the gear used for monitoring: Hegel H30 amps [see p60], a pair of KEF Blade loudspeakers [HFN May '22], and – as it happens – Meze Empyrean headphones [HFN Dec '18]. Much of the finely crafted detail was relayed by the ST-Amp to the Meze 109 PRO, streaming over USB from an iMac running Roon. It was all there with the 'Birds' track, including the large room acoustics, with just a touch of reverb, the impressive soprano singing and the faint whistling darting in and out of the music. Similarly, the texture exposed by the ST-Amp in the baritone saxophone on 'Elephants' was commendable for a DAC/headphone amp at this price point.

'Zu Asche, Zu Staub' is a big-band jazz tune from the soundtrack of Babylon Berlin [BMG 538357890; 44.1kHz/16-bit], and listening to it here proved the DAC and amp stages of the ST-Amp could keep up with fast-paced, largescale pieces. A little more punch and impact would have been welcome when the trumpets and the rest of the band joined in, but the percussion solo halfway through the song made up for this by having the drum kit bounce playfully around my head.

Balancing Act
With the far trickier Sennheiser HD 660S2 (rated at 300ohm with 104dB sensitivity), I quickly moved from single-ended to a balanced cable connection to counter a loss in body and low-end extension. Cécile McLorin Salvant's cover of Kate Bush's 'Wuthering Heights' [Nonesuch 075597914672; 96kHz/24-bit] gelled rather more successfully over the Pentaconn output, retaining the microdetail necessary to place the first bars of singing far away in this large, cavernous acoustic. Neither, I might add, was there any hesitation during the sudden shift to a close-mic'd delivery as the bass guitar enters.

It's more likely that everyday users will press the ST-Amp into service as a full-blown DAC/amp solution, but should you decide to deploy it purely as a headphone driver you won't be dissatisfied. Hooked up to an RME Audio ADI-2-DAC FS, and using closed-back MrSpeakers (now Dan Clark Audio) Ether CX headphones, the amplifier contributed toward a spacious and organic rendition of Antonín Dvořák's Symphony No. 9 in E Minor [Herbert von Karajan, Bibliotheque National de France; 96kHz/24-bit].

Using this external DAC afforded a little more liveliness and presence to the overall sound, indicating that the ST-Amp's analogue headphone stage has more to give. Kx5 [MAU50533A1X; 44.1kHz/24-bit], from the techno collaboration of the same name, uncovered superior full-bodied synths and more impactful beats on 'Alive' with RME Audio's hardware as the digital front-end.

Equally, the 'Complete Masters' release of John Coltrane's Blue Train [CM Blue Note; 96kHz/24-bit] demonstrated conclusively that while the ST-Amp's DAC could be bettered, EarMen's TI-based amplifier is also capable of an 'airier' all-round performance. So, if you are dead-set on a convenient single-box solution, the ST-Amp performs very proficiently straight out of the box, while affording the reassurance of great upgrade potential.

Hi-Fi News Verdict
With its ST-Amp, EarMen once again offers a neat, affordable package to delight head-fi enthusiasts. The amplifier section is up for driving both power-hungry headphones and sensitive in-ears, making it an excellent choice for when your collection starts expanding. The integrated DAC stage performs well too – it's not the last word in engagement but its clarity and fine sense of timing are still a compelling mix.