I've just started using my Mac for music recording (I've got a Tascam US122). The bundled software wouldn't work as I'm running OSX10.2.3 so I'm currently using Audacity. While this is OK, it is slightly limited and there seems to be far more choice for OS9 users.
While earlier Imacs used to boot in OS9 as well, mine only has Classic.
What I want to know is this:
Would it be possible to install a full version of OS9 with no ill effects and boot with that instead, enabling me to use Cubasis etc. ?

Are there any other programmes that I could use with my current set up.

I know this post is a bit involved, but any help would be greatly appreciated.

All newer machines from Apple do not boot into OS 9 so depending on your machine you probably will not be able to boot into OS 9.

As for software to run under OS X (or OS 9) I recommend Metro.

I you can have a real OS9 on your computer (we need the model…) to run 9 smoothly as a system it should be on its own partition. Even better, after install: DELETE the elements in the system folder with "Classic" in their name, it's OSX support and the OS9 can then be used as a classic environement, delete them so that OSX can't make a mess with it.

Once you have this 9 installed, you need FIRST to install OMS (important), then any soft/driver you need (Cubasis, PT Free whatever…)

Cheers
I haven't yet got the model of OS9 I'd like to install as I'm still just finding out if it would work. I'll go for the most up to date version I can get my hands on. So how do I go about installing it on its own partition? I'm really quite new to all this.

Honestly, if you're "really quite new to all this", as you say, I wouldn't bother with OS 9 full stop. The hassle of getting the install discs, partitioning your Mac, tweaking the system and implementing it all correctly so that you don't create even more problems is more trouble than it's worth. IMHO.

I'm not that new to Macs, but I wouldn't even consider it. More choice for OS 9 users? I don't know about that. All the major sequencers (the ones that are most reliable and most widely supported) are all OS X ready. Dozens of companies produce OS X plugs and virtual instruments. New companies are springing up all the time producing OS X-only music software.

If the iMac you have only boots into OS X, it must be a fairly recent model. That means it should be powerful enough to run OS X music software quite happily.

If you have a particular OS 9 app in mind, fair enough. But personally, I can't think of anything that runs in OS 9 only that is truly essential any more. Either it's on OS X already or you can find a perfectly decent equivalent.