Design, Build Quality
The EarMen ST-Amp is a small unit and it measures only 170 x 30 x 150 mm / 6,69″ x 1,18″ x 5,90″. You really don’t need a lot of space on your desk to use the ST-Amp, and it easily disappears as in, it won’t draw your visitors attention to it.
With 1.1 kg (2,42lbs), the units is quite light and that can be a little annoying. The reason I am saying this is because it only stands on 3 feet and it easily moves around on your desk, or leans over to the left and right when plugging cables in on the beck and holding the unit. When plugging headphones in and out, you also better hold the unit in place. I have now stacked the JDS Laps Atom Amp+ HEVI on top of it to make it heavier.
The build quality, as with all EarMen units, is excellent. The ST-Amp is built in Serbia with top-quality materials. The ST-Amp has a full aluminum enclosure, with sharp and precise edges. The front and back panels are perfectly finished and the indicators on both panels are precise and easy to read. The flick switches and connections feel sturdy and sit tight in the unit. The ALPS potentiometer also is a pleasure to work with.
On the back of the unit the RCA connectors are fairly close to each other with some screws in between, so pay attention to that when you’re using nice aftermarket cables with larger plugs. With my Audio-GD cables, there were no issues whatsoever though.
Lay-Out
The lay-out of the unit is simple but it works well. On the front of the unit you from left to right have the power switch, the Digital/Analog input selector, the volume dial, the 4.4mm balanced output and the 6.3mm single ended output. The EarMen name is in the top left corner, the ST-Amp name in the top right.
On the back of the unit you from left to right have: the 4.4mm balanced input, the single ended RCA input, the Single ended RCA output and the 4.4mm balanced output. Next to that on the right you have the digital USB-input. There’s no optical or coaxial input in this unit. Next to the digital section you have the input voltage selector and the fuse / power cable connector.
The top of the unit is completely clear and on the bottom you have the 3 small, sturdy rubber feet in a triangle position.
Usability
It’s very easy and simple to use the ST-Amp. Just plug in your cables and connect the switches on the front to the correct position.
The ST-Amp is very easy to use as a DAC/AMP combo, but it’s just as easy to use as an Amp-only. The unique thing to note here, is that USB is the only digital input available. To run the ST-Amp from your Windows laptop, you don’t need to install any driver, and the setup will be automatic (Wasapi).
Using the ST-Amp as a pre-amp also is very easy, and I have been using it in my speaker setup, as mentioned earlier. Just don’t forget to turn down the volume when switching back to headphones.
Even thought the ST-Amp has two headphone outputs on the front, you can only use one at a time.
Sound Intro
I have mostly been using the ST-Amp as a DAC/AMP combo, hooked up to my laptop running Roon, streaming Tidal. The USB cable used is the “Epic” from The Chord Company. I have also used the ST-Amp in combination with the Musician Audio Aquarius DAC, but for this review we’ll focus on using the ST-Amp’s internal Sabre DAC.
In this review we’ll mostly look at how the unit performs with the most popular headphones on the market, so the focus will be on that chapter.
Sound General
The EarMen ST-AMP is dead silent at all times and there’s a pitch perfect background no ;atter what type of headphone you hook up to it. The ALPS volume control is smooth and precise, noiseless and gives you a lot of headroom to precisely set your preferred listening volume.
What I absolutely love about the ST-Amp are it’s musical and smooth delivery. Depending on the headphone used, it can go to a warmer side of neutral but not overly so. From a technical point of view I absolutely love the stereo imaging and left-right balance.
The EarMen ST-Amp at all times delivers a full sound from top to bottom, but it’s never too thick or unnatural sounding in any way. The overall presentation is spacious and airy and the AT-Amp is in perfect control even during very complex and busy passages.
ST-Amp has a good level of precision and detail, though I feel the internal DAC is holding it back a little here. With a higher-end external DAC, you will elevate the amps performance further.
Bass and sub bass in general are good but higher end amps perform better there with more rumble and precision all the way down. To me the layering and depth from top to bottom probably is the part that could be improved most as it is a more compact and flatter sound. Then again, it’s more than on with what the market gives you at this price level.
In short the EarMen ST-Amp gives you a very musical experience, with an overall good technical level and more power than you will ever need. It’s not the most precise sound on the market with the internal DAC, but it makes up for that with its pleasing, natural, and musically smooth delivery.
Headphone combos
The headphones I chose for this section are the ones that most likely will be used out there in the real world. If there’s a specific combo you want us to try out, let us know in the comments section and we will try to make that happen. Unless specifically mentioned, all headphones were used in balanced mode.
The first headphone for his chapter is the Sennheiser HD 660 S2. To me the HD 660 S2, when correctly driven, is one of the best headphone of the HD 6XX-series. I awarded it just a few weeks ago. Together with the ST-Amp the Sennheiser HD 660 S2 has a full bodied presence from top to bottom, with a softer, smooth (vocal) delivery and excellent bass presence. The combo sounds precise and detailed and it comes with great control, clarity and spaciousness in the delivery. The stereo imaging and positioning is a treat to ears. It’s a setup which is very musical, unfatiguing and so easy to listen to no matter what you’re watching or music you’re listening to. The top end has enough sparkle and energy to keep things interesting, but all-in-all it’s soft on the ears and very inoffensive. I could use this combo all day long and have an excellent musical day.
The second headphone is the Hifiman Arya Stealth and I also love this combo. You here get the same excellent stereo imaging and full-bodied sound, but it is more energetic and lively with more forward vocals and more sparklines everywhere. The note extension and decay here is better, as well as the layering, depth and top-end precision. Where the HD 660 S2 is softer, the Arya Stealth is more explicit with a higher technical level and a more forward presentation. The bass presentation here is fuller in the mids, but the control still is perfect. I often forget how excellent the Arya really is, but this combo is again very easy to recommend. For the money this Hifiman is selling for, it is hard to beat. This combo is more revealing and clear, with excellent energy, vocals and precision.
The third headphone is the Sennheiser HD 560 S and listening to that one is always fun. It’s selling for only €155 here on Amazon, and at that price everyone should have one (like the Beyerdynamic DT770 32). With the ST-Amp you (in single-ended mode) get a full, relaxed and smoother sound that is very easy but pleasant on the ear. It’s somewhat slower and warmer but it’s a very relaxed sound. It’s not the most technically strong combo, and it probably isn’t suited for all musical genres, but it is soft, easy and pleasant to use. A simple and easy to like sound but technically limited.
I have a love and hate relationship with the super popular Hifiman Sundara, and to me it depends a lot on how it’s being driven. The ST-Amp does an “OK” job with it, but nothing more. Like with the HD 560 S it isn’t the most precise or detailed sounding combo. The amount of body and impact is good, and the spaciousness even is very well done. The vocals here are more to the front, with a less smooth presentation. It to me still a rather flat and more condensed sound with limited depth, layering, extension and spaciousness. It’s certainly not the combo that will make me change how I feel about the Sundara, but I do have to admit it sounds very nice when playing Roy Orbison’s Pretty Woman.
The fifth and last headphone in this section is the Meze Audio Empyrean. It’s maybe not the first headphone one would think of using with this combo or at this price level, but we actually found this exact combo multiple times at the High-End Munich show last month. Do check out our show coverage if you haven’t already. You can do so here and here.
The Empyrean and ST-Amp combo is full sounding. Bass is more than present and it comes delivered with good punch and impact. While the bass and sub bass here is controlled it isn’t the most refined and the Empyrean can sound better or more precise there with a higher end, technically stronger headphone amplifier. While the combo is musically strong and pleasing to the ear with superb stereo imaging, it’s clear the Empyrean is getting held back from a technical performance point of view. Think extension, precision, layering. Even though this isn’t the best source for the Empyrean, it still is pleasing, soft and natural to the ear. It’s a very musical and easy to listen to combo which is hard not to like, but if you’re out for a better technical performing Empyrean, you still need to look elsewhere.
The headphone I liked most with the ST-Amp during my tests is the Hifiman Arya Stealth. It delivered the best mix of technicalities, musicality and energy. That said, the Arya sounds even better on the CH-Amp, which brings us to the next chapter in this article.
On the third page you’ll find the comparisons and conclusion. Click here.
Page 1: EarMen, Intro, ST-Amp, Specifications, Box & Accessories
Page 2: Design & Build Quality, Lay-Out, Usability, Sound pt. 1
Page 3: Sound pt.2, Comparisons, Conclusions, Summary
