Hermes has released an alpha version of his new cdda, mp2 and mp3 decoder. Whats most interesting about this app is the ability to rip audio cds to mp2 audio format right from your ps2 and onto your ps2 hdd. So yes folks, this will run independently from your hdd.
Currently all the documentation is in spanish. Translation coming soon.
you can download mp3station at the official thread at ps2reality.net.