Please help!! I need help with my MS 10?

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Hi,

This is my first time on here...so hi everybody,

I have recently bought 2 awesome MS10s. I totally love them..especially when they are hooked together...the only problem is that when I have been trying to record them through my Mbox they seem to be omitting a high pitched interference noise which it horrible and very audible!
None of my other synths make this noise and I have checked all my cables.

I have a feeling that it could be something to do with them not being well grounded?? Does anybody have any easy steps to grounding an MS10?
I really appreciate any ideas/help.

Thanks,
Lucy