OBS is a fantastic free piece of software for all your streaming needs. It's what I use and it works brilliantly.
Conventionally I think people used the Edcast plugin for Winamp to do CaB Radio, but IIRC there's a bit of faff involved to set it up so you can talk on a mic as well as play music.
Re. OBS - I've seen a few suggestions online that it might be possible to stream from OBS to a Shoutcast server (which is what CaB Radio is on), but it's not solidly documented anywhere. Would be worth a crack at testing it though, if someone wants to try it out with the stream credentials.
OBS is primarily for streaming video+audio (via RTMP), but it's not implausible that a Shoutcast server could pick up the audio portion of the stream.
And yes,
OBS is a fantastic bit of software (and free), with its own audio mixer and VST support amongst loads of other features.