Pc Specialist are a big company North of England with a good reputation and yes I got it online.
The good reputation amongst whom? Do they sell to people recording Classical music audiophiles or do they sell to the crowd that listens to their music on smartphones?
Technically your box is a high-end gaming machine with only one graphic cards plugged in where two are expected. It completely doesn't make sense technically. If you maybe read a good reviews of this box, it was because of bribes, not because of any real quality.
This motherboard was especially designed for top-of-the line gaming boxes for the two main graphic card vendors:
https://en.wikipedia.org/wiki/Scalable_Link_Interfacehttps://en.wikipedia.org/wiki/AMD_CrossFireXIt is like selling you a 12-cylinder sports car and only installing 6 spark plugs because you won't be racing, only driving to church on Sundays.
I never used this particular board but some older ones with similar on-board audio section: in a separate metal shield and additional built in voltage regulator. They had better-than-the-CD quality right in-the-box, there was no need to buy any out-board gear to record 2-tracks at a time and produce 5.1-track mix; which was what we mostly did.
Have you actually tried direct audio-in and headphone-out straight to/from the motherboard?
If you just looking for somebody to tell you "buy more crutches" (sorry, Behringer Hum Destroyers), it is not going to be me. Those devices never make sense in any studio work, even if it is a home studio. They are good for e.g. gig at a pub where you get electrical interference from the beer refrigeration equipment; or similar situation where tickets were sold and the show must go on.
Sorry I wasn't able to help you more. I kinda like playing with electronic gear, but I'm never going to care about "reputation" when the proof-in-the-pudding stinks.
Edit: Added links to Wikipedia.