It's decent until it inevitably breaks.
I've owned the GSX 300 for just under a year at the time of this review and all I can say that this DAC would've been fair for its price but the product is just completely plagued with design issues and faults.
For months now, many owners of the GSX 300 including myself have been facing repeated issues where the DAC randomly shuts itself off and has to be unplugged/plugged in again to restore working order. On top of this, there is a chance that the DAC completely glitches out which results in a TERRIBLY loud crackling static mess that can be fixed the same way as before.
The audio driver/software is not that great; it is common for some of your settings not to save for the next time you launch your desktop, meaning you have to set it all up again.
In the end, my DAC finally decided to break itself and refuse to turn itself back on at the time of review, just less than a year of owning it. This product is extremely disappointing coming from Sennheiser and in my opinion, should