Issue: I recently started to get some static noise, sounding like my HDD and a ticking sound every second through my DAC. This noise is not present when other signals not from the PC are being sent through the amp. The noise is also present when outputting from front audio and back panel audio out. It can only be heard through the amp and speakers, not headphones. I've even tried MTH-m50's at full and couldn't hear it.
Background: I have recently moved my system from an old case to a Fractal Design Arc Midi R2, and have had a graphics card failure which has been replaced. Since changing the case (which also happened shortly after moving houses) the DAC developed this noise. You can hear it when listening to most music.
Case, Arc Midi R2
XFX 550W Pro PSU
Amp: JA-S31 powering a pair of Mission 731's. Fed by 5 meter 3.5mm to RCA
So far I've disconnected all HDDs, all connections to the front panel, all USB devices bar this one, this reduced the noise but it was still there, including the ticking. Moved it around through all USB connections, front and back. I have tried disconnecting the fan controller, which affected noise a bit. But they all still leave the ticking and a noise which can be heard listening normally,
Testing the DAC itself through a laptop the noise is not present (on battery anyway, but that's a well known ground loop issue anyway).
The amp is on a different mains loop itself to the computer, both are going through surge protectors and 1 extension cable.
I'm at my wits end trying to figure this out. I'm fairly sure its the case, but all the cases cables seem better isolated than those on the old one. The only alternative is a USB2ISO, and that's currently too expensive for me atm.
I could try ferrite cores around the RCA cable, but I've heard ferrite cores do not work well with USB cables carrying audio. Could try a better USB cabled with better shileding, but what brand?
Any ideas to try?