EPOS GSX 300 review: Slim size, slim pickings

Sennheiser's gaming brand is offering a small amp/DAC combo that promises to take your audio to the next level. Does it deliver? Our review.


Recently, some brand shifting has occurred within the Sennheiser family of products. Now, the former gaming division of the company goes under the EPOS brand name and the folks at EPOS sent over their new GSX 300 USB sound card for testing. Featuring a 3.5mm headphone jack, 3.5mm mic input, and an illuminated volume knob, the GSX 300 promises to elevate audio performance compared to solutions integrated into your motherboard or laptop. 

Plugging in

The EPOS GSX 300 is efficiently packaged in a small box that contains the device, a micro-USB to USB type-A cable, and paperwork. The device is powered entirely by USB, so no need for an additional wall wart to clutter up your wiring situation. On Windows 10 machines, the device is plug and play and requires no driver installation for basic functionality. Some of its advanced features will require you to install the EPOS Gaming Suite on your PC. This software allows for EQ adjustments, mic input fine-tuning, and setting the operating parameters of the only button on the device, dubbed the Smart Button. The EPOS Gaming Suite also offers an online firmware update feature for the GSX 300. Upon installation, I was prompted to update the firmware and began testing using version

The GSX 300 is rather simple in design, which works for its size and intended application. It can be placed on your desk and is small enough to avoid being a bother. The volume knob works as a stepped digital attenuator that simply adjusts your Windows system volume rather than an analog pot. As you turn, it clicks, with each notch offering 2 steps (out of 100) of volume adjustment. Each interaction with the knob brings along a popup window on your screen indicating the system volume level along with persistent play/pause button and forward/backward track skip buttons. It is unobtrusive during normal desktop use, but I wish there was an option to disable the popup.

The included Smart Button can operate in one of two modes: toggling through EQ presets or swapping between 2.0 stereo and simulated 7.1 surround modes. The volume knob is illuminated in blue when stereo mode is active and red when surround mode is active. These mode swaps can also be toggled manually within the EPOS Gaming Suite and the surround mode has an additional Reverb slider that determines how much the imitation room effect is applied to the signal. As far as I can tell, there is no way to get the GSX 300 to actually accept a real 5.1 or 7.1 surround input signal, so its surround mode offers nothing more than room acoustic simulation. I found using the Smart Button to be worthless for toggling surround mode on or off, as the audio output would remain unchanged even if the light color changed. Only when I clicked the toggles within the EPOS Gaming Suite did the audio output actually change. 

Another quirk I noticed is that there is no way to select the sampling rate of the GSX 300 in Windows 10 after you install EPOS Gaming Suite. The device is advertised as supporting 44.1KHz, 48KHz, and 24-bit 96KHz operation, but there was no way to swap to these modes after EPOS Gaming Suite was installed. After I uninstalled the software, the drop-down menu in the Windows 10 sample rate selector became available. I tried testing with foobar’s WASAPI output and the Amazon Prime HD application to get 96KHz playback from my own music files or from streaming, but it was not possible with EPOS Gaming Suite installed. The software does not show an icon in your taskbar while it is open, so finding it in a stack of windows can be annoying compared to literally any other software on your PC.

Users interested in music listening, whether it be high-resolution or things like Youtube and Spotify, would be better off looking for something else as the headphone amplifier in the GSX 300 is underwhelming at best. I tried it out with a range of headphones I had on hand, including multiple Sennheiser models. For music and game audio, I swapped between the Sennheiser PC37X gaming headset, Sennheiser HD598 C, Sennheiser HD598, Sennheiser HD280 Pro, Sennheiser HD650, Sennheiser HD6XX, Philips SHP9500S, Philips Fidelio X2HR, Hifiman HE-4XX, Audio Technica ATH-M50, Audio Technica ATH-A900, Audeze Mobius gaming headset (wired mode), and HyperX Cloud II.

With few exceptions, the GSX 300 failed to offer any benefit over the built-in headphone jack on my main PC’s motherboard and, in some cases, offered lower overall volume output. Anyone using higher-end headphones (particularly Sennheiser or Hifiman) will struggle to get output that runs higher than indoor conversational volume. While it can offer a cleaner, lower-noise sound for people who have EMI interference or other issues with their built-in sound solution, buyers should not expect a transformational experience. While my current motherboard does not have any noise issues, I did swap in a USB sound card dongle I got from Amazon that sells for around $8 to compare to the GSX 300. The audio quality was not materially different coming from the cheap, imported dongle than it was from the EPOS and the cheaper dongle would solve internal noise issues the same as any other external USB sound device. Granted, the dongle did not have a dedicated volume knob, but since it also simply adjusted Windows volume, it offered the same basic user experience. The EPOS Gaming Suite does offer some mic input adjustments, but these filters and effects are already present in virtually all other applications where you would need them (TeamSpeak, Discord, OBS, etc).

Because it lacks any additional fixed-level output, the EPOS GSX 300 is also less than ideal for users who often swap between headphones and desktop speakers. You will have to swap cords every time you want to change between listening options just as you would with simpler integrated motherboard sound solutions. Anyone who reads my reviews understands how much I love knobs (insert Steve Harvey face meme here) but the knob on the GSX 300 adds almost no value to the package thanks to the visual volume level pop up, the digital attenuation, and its lack of texture.

Closing thoughts

The EPOS GSX 300 can be had for $80 from a variety of online retailers. The value proposition the device provides at this price is rather murky. It fails at being a solid headphone amplifier, advertises 7.1 output without being able to accept 7.1 input, has a single button that is nearly worthless and fails to offer a compelling volume knob. It can clear up noise problems for users suffering from electrical interference inside their PCs, but so can any number of USB sound cards. It is easy to install and its compact frame will fit on any desktop. Some users will find value in the knob illumination or may want to get a matching brand sound card to go with their EPOS headset. I find it hard to recommend for most other use cases and particularly for music lovers with higher-impedance headphones. 5/10 brown notes

Contributing Tech Editor

Chris Jarrard likes playing games, crankin' tunes, and looking for fights on obscure online message boards. He understands that breakfast food is the only true food. Don't @ him.

  • Easy to install
  • Can eliminate noises issues in certain cases
  • Easy to find a spot for it on your desk
  • Underpowered headphone amplifier
  • Software quirks and bugs
  • Smart Button offers no value
  • Surround simulation is gimmicky at best
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