Reply to S4 to KRK RP6 G2 - balanced?

Hey guys,

While waiting for the S4 to arrive I've gotten myself the RP6 speakers. I've checked out the Know-your-connections post and the cable-pizza post but there's one thing I am not sure of.

I got the choice of going balanced XLR or TRS (or unbalanced RCA but somehow that doesn't feel 'pro') on the RP6. Now I know the S4 doesn't have XLR but it does have balanced TRS so when I was in the shop today asking for some balanced 'jack' cables (didn't know the proper abbreviation, TRS, for it) I ended up with what appears to be 'mono' plugs. Now I was told by this friend this probably isn't the right cable as I should be gettings jack plugs that appear to be stereo plugs, with 2 rings.

Am I right that they alway appear to be 'stereo' jacks in order for them to be balanced? For the "cold" ring bit? Or do 'mono' jacks also exist as balanced plugs? Mind you when I refer to mono or stereo I mean the look of the actual cable, not the signal going through it as I realize that is mono by definition.

Cheers!