[WTD] Borrow or buy: RCA shorting plugs

[gustav_errata]

I've become obsessed with trying to resolve a hum that I get from both of my studio monitors (I can hear it from the cone but also from the sidewall if I place my ear to it). It doesn't appear to be a ground loop as it occurs with no inputs connected. An iFi DC Blocker failed to attenuate it at all, theoretically ruling out DC induced transformer hum. I still have more things I can test of course.

Current hypothesis: each monitor has both a balanced XLR and single-ended RCA input which are simultaneously active (no switch between them), so perhaps the unused RCA inputs are causing problems.

Does anyone have some RCA shorting plugs lying around that I can borrow to test this idea? I know they're generally cheap but I figured I'd see what's out there first.

(The hum is pretty minor and I only notice its absence when I shut off the monitors and I feel my whole body relax. So, this isn't urgent)

 

[Neil P]

Hi please pm, happy to lend you some for cost of postage.

 

[a.palfreyman]

I can hear it from the cone but also from the sidewall if I place my ear to it). It doesn't appear to be a ground loop as it occurs with no inputs connected.

Sounds more like transformer noise is energising the cabinet. I assume each has its own amp/transformer?

each monitor has both a balanced XLR and single-ended RCA input which are simultaneously active

Don't run you preamp into it with shorting plugs fitted if the above is true as this may effectively place a short across the preamp.
Might be better if this were in the diy or audio sections with a different title. Maybe start a new thread?