It's something that's already on my to do list but more needs to be done so we move away from the Winamp core doing the playback & it's then WACUP managed & such things can then be baked into the core (cross-fading is another thing that needs to be natively implemented instead of often only being done at the output stage which isn't useful for personal streaming).
There might have been an old plug-in that can do it (which would likely just insert a forced sleep instead of proper digital silence) but I've not been able to find anything from a quick search.
-dro