From the first page,
www.smoothjazz.com, if I click on Winamp icon, FF opens a new page and it connects to
www.winamp.com. I do not get music there.
If I click on the Listen Now button, I get a pop up, and get connected through FF , not sure what plugin it is using, but it is not playing through any player on my system.
To get it to play through a player on my system, I had to go to the streams page, click on the top button For MAC + PC, I got a pop up, I selected download. That downloaded a .pls file. I opened that file with Totem Movie Player 2.30.2 and it plays the stream in the .pls file. I did try Audacious, the music player I use the most, but it will not play the stream.
I do have the mplayerplug-in 3.55 installed in firefox. It supports .mp3 streams, that is my best guess as to the plugin that is playing the Smoothjazz stream.
I do not have WinAmp installed. I used it a long time ago, but not recently. I stopped using Xmms, since the development for Xmms seems to be gone.
I hope this gives you some options, and you get the stream playing.