This and im sure your knowledgeable on grounded verses non-grounded lines in your signal path.  You can also get hum if you plug an ac utility on the same circuit as your audio equipment.  For example if im listening to music threw my mixer and pa and i plug the vacuum in the wrong socket i get WICKED noise interference.  This being an old ass trailer makes it a similar situation, half my power sockets dont work...

I'd go the extra step and grab a power conditioner instead of a surge protector

also, read this

at sound school they told us to make sure equipment was on separate circuits. But, TBH short of just isolation I could never really understand the reasoning.

but then a mastering engineer friend turned me on to the magic of the ground loop isolator

(edit) never mind, I misread.

but here's more info than you ever wanted to know

My computer doesn't even have a ground pin. Does yours have one? Japanese plugs are like american. Perhaps that is why it hums.
I get all sorts of frigging hum now, this didn't happen in Argentina. I think these british houses are cabled like absolute ass.

My set up in my current apartment hums like a mother fucker because there aren't any accessible ground points. The only plug socket with a ground is on the balcony with the washing machine, it is a really odd building about 40 years (pre historic here) old which was originally offices and kind of badly converted to apartments.

In a month I am moving to a new place which has grounded plugs in every room, yay! my set up is basically, a few synth modules, a couple of game consoles, powered speakers, mackie mixer, PC and Monitor. I assume. My plan is to just buy a power strip with a ground, plug the monitor/PC/mixer into the grounded power strip then plug the strip into the grounded plug. I assume this is a good idea?

Reason I ask is, as far as I can work out, ground loops are where items are being grounded to different points, my (very very) rudimentary knowledge of electrics assumes that a grounded power strip counts as a single ground point?

A couple of other questions, I am 99 percent sure, after unplugging various items in turn, that the problem is the PC but aside from the PC/Mixer and monitor, are there any other items which are likely to need grounding?

Last one! can safely (hum wise I mean, I know it won't explode) mix, grounded and non grounded items in the same power strip grounded powerstrip?

Also do I win the prize for repetition of the work "ground" in a single post?