Like these?
Am I the only person that looks at that and thinks "that's just wrong" ?
It is quite useful. My present portable AF oscillator is a Fostex TT15, and it's got RCA out. With a BNC adapter, you're good to go.
Apart from that, RCA connectors only have virtue as "better than some others" (like the Belling-Lee). Much prefer the XLR, with a good pair cable. In them I like Mogami, Sommer, and the HST-M that Canford have sourced. Monster is just fooling nervous musicians, a particularly strange kind of 'phool.
If one
needs RCA, it is worth going to the trouble of buying Neutrik "Profi" RCAs and to connect them with RG62 or similar. Now that's a hifi cable much better than most audiophools crap. I have a pair of such "interconnects" (fancy audiophool name for "short audio cable") that I've made myself, and they are both sturdy and have survived for some time. No problems with sound either -- as a matter of opinion (no facts here) I much prefer them to cheap "stereo" cable.
Of course they're insanely expensive (not compared to 'phool stuff though), but they're good enough for me, and very easy to work with.