Just use RCA’s to XLR man, you’ll be fine. Don’t sweat it. If you’re that worried get some decent well insulated cables, also plug your speakers into an independent plug socket (don’t use socket doublers and run other gear off the same socket). Just plug em in and have a listen, if there’s interference or horrible humming then you might wanna rethink your set up but I highly doubt there will be.
Also, not having balanced cables on your speakers won’t make any difference to your final mix so I really wouldn’t worry too much about it.