Umm.. I have Amplifier 2.34 in use. The mentioned stream works just fine. Just select "Open URL..." from menu or keep LMB pressed on playlist's "+" button and select "URL". Then paste the url on the requester and start playing. It should also work with Amplifier from OS3.9.
BTW. check the rexx/ directory in Amplifier's dir. There's scripts for .pls and .m3u, which you can integrate to your favourite browser. After adding those to browser's mimetypes, you can play shoutcast etc streams just by clicking them on browser. No need to save anything anywhere.