I have four basses - 3 active basses and one passive.
I run my basses through a Behringer U-Phoria UMC22 and can hear a slight humming/buzzing sound on all my active basses (the passive bass is clear as a bell). The buzzing goes away when I touch the strings or volume control on on the basses or if I bring the Behringer up close to the bass (like within 30cm of it).
I’m not sure it’s a grounding issue as it’s happening on all the active basses - having said this, I know zip about electronics and how they work. Can anyone offer suggestions on how to resolve this. I don’t think I really used to notice it. But since I upgraded the pick-up on my Squier Affinity PJ (passive) it’s so clear that it makes the humming so obvious on the others.
PS: RIP to the great man, Charlie Watts