Most likely not compromising the signal in any meaningful way. RCA is unbalanced, but that won't affect anything as long as you don't have an extraordinarily long cable run from your interface to your monitors.
My advice is, especially if you've been using the headphones and bookshelf speakers for a while and can get relatively decent translations of your mixes (ie you've learned your current monitoring system), then hold onto them until you've saved up for another step up in the price range from the m-audios.
Those m-audios will be noticeably better, but you aren't anywhere near the point where the price/performance ratio starts becoming too large (that is, the point where you're paying a couple thousand more for a miniscule improvement).
The set of speakers you'll be able to get for $500-$1000 will be as much better than the m-audios as the m-audios will be than your current setup (try and parse that sentence!

) And it will take you as long to learn those m-audios as it will to save up for the next step up from them.
Basically, I'm recommending you skip the entry level studio monitor step altogether and wait until you can take the step above that, as it will be entirely worth the extra time and money you invest in that better pair of monitors.
Then again, this is all just my opinion/how I would have done it had I known then what I know now.
Good luck either way.