Yes, you won't notice almost anything in CPU load with Delfina playing mp3. Just small usage depending which player you use (does it have gui etc).
And remember to disable all meters etc from player! They're just waste, because there won't be any data back from Delfina, which would be shown in those. I first wondered why Amplifier made some kind of CPU load when playing with Delfina, but then I noticed that having one scope selected it used it even when it didn't show anything.
Couple of programs:
http://de4.aminet.net/mus/play/DelfMPEG.lhaStandalone mp3 player for shell. ARexx and signal support, so you can make own guis or whatever.
http://de4.aminet.net/mus/play/dmdev.lhampeg.device compatible device for Delfina. Can be used with Amplifier, Frogger etc.
http://it.aminet.net/mus/play/mhimdev.lhaMHI driver for mpeg.device. Needed if you want to use AmigaAmp.
http://it.aminet.net/hard/misc/DelfTweak.lhaOverclocking utility, if you have older Delfina (like Lite or 1200) and have problems with high bitrate mp3 files.
http://it.aminet.net/util/misc/DelfInit.lhaBetter initializing program. I don't know if it's needed nowadays still...
And get the latest delfina.library from Jens's page.
And if you still get some freezes with mp3 (usual with Delfina Lite card) then this helps
http://jpv.wmhost.com/delflib_patch_2.lzx
