First a question. Is there a program which will allow me to edit PSID (c64 tracker) files on the amiga. I have been intrigued by a program called SIDM.O.N. which makes my a1200 crash!
Now...
I love using my amiga for sound generation and composition because I can enter my notes in REAL-TIME from the QWERTY keyboard. I have not found a PC program which is as responsive as ProTracker or OctaMED 4ch. I understand that this is due to fundamental limitations with the standards set by IBM back when dinosaurs roamed the earth.
Also, I notice that MOD. files just don't sound as cool on a PC as they do on an amiga. The amiga has some nice fat bass!
If you have an accellerator or sound card (or both) then DigiBooster, Symphonie and OctaMED soundstudio are usable. Otherwise you will probably be frustrated with their incredible SLOWNESS! But really, if you want that proffesional sound then you may as well be using PC or MAC.
for 303 type sounds then you would be wanting:
303tracker (or it's earlier incarnation 303emu) does one of the most accurate 303 emulations of any I've heard on any platform. But I think you would be needing some fast-ram to run that one!
or...
The latest version of Kocmu runs nicely in the background, as it does not use the audio channels itself. It uses minimal CPU, and it also includes some C source for the 303 emulation routine it uses. Handy if you want to learn how to synthesize your own sounds (as I have been doing). I seem to recall seeing a REAL-TIME version of this program for 060 Amigas, but have never used it myself.
Both these programs can be found on Aminet. Indeed, you could do far worse than to trawl the aminet for software if you are looking to do ANYTHING on the good old Amiga.