Audio interference when amp is plugged in motherboard

[Racinglife12]

Hello

I have a slight issue with my amplifier when its connected to my motherboard.
Theres a lot of interference when I move my mouse or when things happen on screen. The only way to get rid of it a little bit is to turn the volume knobs on my amp below 5 (they go from 1 to 10)
Its not a traditional all-in-one amp.

I've tried it on 2 diffrent motherboards (I upgraded in the time that I had the amp) and the same thing keeps happening. This doesnt happen when its plugged into my laptop or phone, then the interference is completely gone.

Specs:
CPU: Intel Core I5 6600K
Mobo: Asus Z170 Pro Gaming Aura
GPU: Sapphire R9 390
RAM: G.Skill Ripjaws V 16GB 2133Mhz

Amp: SoundTech PL602
Mixer: Devine MX-4
Speakers (for the ones who are interested): 2x JBL TR125

Should I get a sound card to get rid of the problem or should I invest in better cables?

Thanks

 

[TMTOWTSAC]

Any chance it's ground loop hum? Is the amp plugged into the same outlet/strip as the desktop?

 

[Racinglife12]

Any chance it's ground loop hum? Is the amp plugged into the same outlet/strip as the desktop?

No not that I'm aware. We've tried both in the same strip and even another power fuse and still the same results. I'm really a newb when it comes to audio stuff