Marakanetz,
There are two big variables with your question, one we (those of us out here in Audiogonland) can't possibly know and one we can at least guess at. Broadcast vs. streaming for any station will depend on the quality of the broadcast signal at your location and the quality of the stream the station provides.
If you can get a great signal where your rig resides, then with a great antenna and a great tuner you'll get a very high quality listening experience. Same with streaming; if you get a high bit rate stream with a great DAC, it will sound great.
Conversely, if the broadcast signal is lousy/noisy/compressed/multipathed/whatever, no matter how good your antenna or tuner, it will sound lousy. And a low bit rate strram will sound bad through even the best of DACs.
My experience is that with a good signal/antenna/tuner (I have good signal for 2 out of the 3 stations here) then the broadcast source will be better unless the streaming rate is great than 128k. One of the stations with good signal (KLCC) streams at 80k MP3, so the broadcast signal is demonstrably better. The other (KWAX) streams at 256K AAC, so no contest, the stream is better even though the broadcast signal sounds great.
The third station is a push, as the broadcast signal is only so-so, but they also only stream at 64K AAC+. On a good day, the broadcast signal is better. Other days, I listen to the stream.
Your WUSM has 3 different streaming options. 24k MP3 is horrible. 128k MP3 is pretty good, and will be better than broadcast with a lousy signal but probably not quite as good as broadcast with a great signal. 128k OggVorbis is the wild card; I listened to it and it sounds pretty amazing. It may be better than any broadcast signal, as the OggVorbis codec is really good.
Bottom line is my experience says there's no simple answer. I listen to both broadcast and stream and have for years; it just depends on what I'm listening to and what's available. There are lots of great Internet only stations that I listen to on a regular basis, but I listen to broadcast signals every day.
By the way, all the usual analog vs. digital caveats/arguments apply. Did the "analog" broadcast signal you're hearing pass through an ADC somewhere in the signal chain? That's a discussion for another thread.
David