Q My Retina MacBook Pro outputs audio through a Steinberg UR22 interface to high-end powered monitor speakers. When I connect the USB interface there is a loud, variable buzzing in the speakers. Is this a power supply or grounding problem?

A Some early serial numbers of this interface had an acknowledged fault which entitles owners to replacement. However unwanted noise seems to be a not uncommon complaint from later UR22 users too.

If it is a ground/earth problem or noise coming through a cable, you should be able to attenuate if not fix the noise by using a screened high-quality USB cable, well-screened output cables to the speakers, installing a ferrite noise suppressor on the mains supply cable for the UR22, and running all devices from the same mains socket (or, sometimes, from different ones!).

If the noise persists it suggests that there is an internal fault in your audio interface, possibly a damaged ground connection or failed capacitor(s). Sadly there are still plenty of sub-standard capacitors that sneak into electronics and cause all manner of problems. Contact Steinberg and get them to check your interface out, or invoke its warranty.

Updated from the original, which was first published in MacUser volume 31 issue 1, 2015.