EPOS GSX 300 External Sound Card Review

Manufacturer: EPOS EPOS GSX 300 External Sound Card Review

The GSX 300 from EPOS is a compact external sound card with both 2-channel and (simulated) 7.1-channel surround modes, and it offers customization of various sound options via the EPOS Gaming Suite software.

With separate 3.5 mm analog headphone and mic jacks, the GSX 300 is positioned as a digital interface for analog gaming headsets. It can also drive standard headphones, of course, essentially doing the work of an outboard DAC and headphone amp pairing.


Key Benefits and Features:

  • High-resolution audio – Easy to install external sound card delivering high resolution audio for acoustic clarity and audio realism
  • 7.1 Surround Sound through PC Gaming Suite – PC Gaming Suite with customizable 7.1 surround sound lets you set sound profiles for different games by balancing and focusing frequencies where they are most needed.
  • Intuitive design – Large manual volume dial for adjustments on the fly, customizable smart button to flip between sound modes or profiles and LED indicator to show which in on.
  • Synchronized with Windows 10 sound – Automatically synchronizes with Windows so you can see how loud you are playing
EPOS GSX 300 External Sound Card Box
Product Specifications
  • Supported Sample Rates
    • Main Audio: 24 bit, 96 kHz
    • 7.1 Mode: 16 bit, 48 kHz with EPOS Gaming Suite
  • Audio outputs: Headphones
  • Recommended headphone impedance: 25 – 75 Ω
  • USB standard: USB 2.0
  • Total harmonic distortion: < 0.01%
  • Cable length: 1200 mm
  • Connector plugs:
    • 3.5 mm headset socket
    • 3.5 mm microphone socket
    • Micro USB
  • Compatibility: PC
  • Warranty: 2 years, international

$79.99 USD

Manufacturer Description

“The gamer seeking enhanced audio performance instead of relying on their PC on-board sound will find excellent value in the GSX 300 external sound card. Paired with a gaming headset, the GSX 300 together with the EPOS Gaming Suite delivers digital sound processing and customizable 7.1 EPOS Surround Sound. An LED ring around the volume dial illuminates blue for 2.0 and red for 7.1 sound mode.”

Usage Impressions

Plugging in a moderately high-end pair of headphones – Audio Technica ATH-AD900X – I evaluated the sound quality with uncompressed audio, up to the maximum supported 24-bit / 96 KHz. And before proceeding, I’ll mention that these AD900X headphones, with 38 ohms impedance and 100 dB/mW sensitivity, are easy to drive.

Obviously this GSX 300 is not marketed as an “audiophile” product, but I like to use familiar headphones and music to provide a initial quality impression. The AD900X headphones revealed limited dynamics from this small unit, creating a somewhat “congested” sound in complex passages. I tried a few things, adjusted EQ using the EPOS software, but louder passages still seemed to hit a wall. What sort of amplification was driving this headphone amp?

I’ll add that S/N seemed very good with the GSX 300 and there was no extraneous noise in either operating mode. I did note that both of the laptops I compared this unit to offered greater headroom from their built-in 3.5 mm headphone jacks. It really seems that my opinion of the sound always comes down to power, and it feels like it’s being pushed even at what I consider to be normal listening levels.

From the software screenshots above you can see that there are multiple EQ presets in addition to the stereo/surround modes, and mic input also gets some software control with “voice enhancer” modes and background noise rejection options.

Rather than continue on with my subjective impressions – backed up by zero empirical data as I lack measurement tools (the gold standard is, of course, Audio Science Review) – I decided to take the GSX 300 apart and let the internal components tell the story.

Inside the GSX 300

After removing the rubber-like pads from the bottom there are two small screws, and two small plastic tabs. Once the font panel was freed the case was pretty easy to pull apart.

EPOS GSX 300 External Sound Card Teardown

We are dealing with some very small internal components here, and the majority of the device is empty. It gets its reassuring weight from a metal plate in the bottom, which is a nice touch and does help keep it in place on your desk (along with the soft rubber-like skids on the base).

EPOS GSX 300 External Sound Card Teardown 2

I can’t help but feel that the headphone and mic jacks could easily have been positioned on the front of the device, with a blank area (visible to the left of the upper PCB in this photo) offering plenty of real estate for two 3.5 mm jacks. I won’t argue too much – the short signal path is probably a good thing, particularly when you see what is powering this.

And now the main event, a tiny chip on the surface of the board that contains the input/output jacks:

EPOS GSX 300 External Sound Card Teardown 3

The chip at the heart of the GSX 300 is the Conexant CX20988, which is described as “a highly-integrated, low-cost USB audio CODEC that is optimized for USB Type C headset applications” in the datasheet (PDF). This component selection seems to validate my impression that the sound from this unit lacks power, as a CODEC like the CX20988 would typically be found in a tiny USB-C to 3.5 mm adapter, and not a dedicated headphone DAC/amp.


The GSX 300 is a very small, nice looking external audio device that will add both 3.5 mm headphone and mic jacks to any system with an available USB port. The volume knob is a nice convenience, as is the programmable front mode select button – which defaults to a switch between the stereo and surround modes. And there’s even a color change to show which mode you’re in: blue for stereo, red for surround.

Ultimately a review of an audio product is more about the sound than the features, and while certainly a competent solution I didn’t find the unit to offer much “punch”, particularly when listening to complex passages or those mastered with a wide dynamic range. The stereo mode sounds better, with the 7.1 mode sounding a little boxy in my opinion (I didn’t play around with the optional reverb setting, to be fair).

If you need analog connections for a system (particularly a laptop) that doesn’t offer them, the GSX 300 can certainly offer a solution. I’d like to see it below the $79.99 list price, but the market will decide on this point. I am spoiled by more expensive audio equipment, but – speaking subjectively – this device is probably not an upgrade over most midrange to enthusiast-level motherboard audio.

I would love to hear a higher-end take on this product from EPOS, though they have such impressive wireless sound quality (the GSP 370 is an outstanding pair of wireless headphones, regardless of application) that a device like this is not always required.

Review Disclosures

This is what we consider the responsible disclosure of our review policies and procedures.

How Product Was Obtained

The product is on loan from EPOS for the purpose of this review.

What Happens To Product After Review

The product remains the property of EPOS but is on extended loan for future testing and product comparisons.

Company Involvement

EPOS had no control over the content of the review and was not consulted prior to publication.

PC Perspective Compensation

Neither PC Perspective nor any of its staff were paid or compensated in any way by EPOS for this review.

Advertising Disclosure

EPOS has not purchased advertising at PC Perspective during the past twelve months.

Affiliate Links

If this article contains affiliate links to online retailers, PC Perspective may receive compensation for purchases through those links.

Video News

About The Author

Sebastian Peak

Editor-in-Chief at PC Perspective. Writer of computer stuff, vintage PC nerd, and full-time dad. Still in search of the perfect smartphone. In his nonexistent spare time Sebastian's hobbies include hi-fi audio, guitars, and road bikes. Currently investigating time travel.


  1. Operandi

    So…. $80 for an IC that probably costs low single digit $s, some misc connectors, switches, and a plastic housing? Nice profit margins there….

    Also, personally if I’m going to put an external DAC / soundcard on my desk I want it to have line out for speakers especially at this price but I guess Sennheiser probably wouldn’t care about that.

  2. JAMF

    No mic in. Who thought that was a good idea? It has become more evident in these times, with meetings over Teams/Zoom/Skype/Etc. It is competing with something like a mayflower ARC one one end and BT headsets like Sony 1000MX3/4 or Bose QC35 II on the other… and failing.

    • Sebastian Peak

      Yes, mic in. 3.5 mm.


Leave a reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Latest Podcasts

Archive & Timeline

Previous 12 months
Explore: All The Years!