- On Mac OS9.1 there are several things you could do to optimize the audio. Installing a fresh OS can be a good idea especially when it's a 'second' hand machine.. you never know what the former owner has done to the machine.. so here are some things you can do to get the machine healthy, whatever what's wrong with it.
1. Zap the PRAM. (Start up your machine holding Command+Option+P+R ) Do this 'till you hear the statrup sound twice. It will re-init all settings in the battery powered RAM.
2. Run Norton Disk Doctor. To fix drive errors if there are any.
3. Run virus detection software. You never know.
4. Rebuild the desktop. (startup holding Command and option)
Instead of 2&3&4, you can reformat your drive and set up partitions as well. I would advice you to have several partitions, so you're able to install OSX very easy later on. Although it's supported by apple that you have several OSes on the same partition, it's generally better and easier to have different partitions for each OS you're running. And if you don't need previous data, it's the best thing to do as it solves every possible problem in one go.. if you're at it, a low-level format is the best way, it takes a lot of time, but you will be sure that the drive is like brand new.. normally you will never need to do this again (you don't even need to do it rightnow, but it would be a good precaution, because you don't know the machine).
5. Re-install the OS. You can keep OS9.1 or go to OS9.2.2 (updates from 9.1 to 9.2.2 are available from the apple website.. if you're planning on going OSX later on, make sure to install OS9.2.2.. avoid 0S9.2, it's buggy, go directlly to 9.2.2.). Re-installing an OS is a pretty easy thing to do. Insert the OS disk and boot up holding 'C' to startup from CD-Rom. Press install, and off you go..
6. Ditch unnecessairy extensions and control panels. Use the extension manager (in the control panel) for this. You can get a little description about each extension and control panel, helping you to select what can go and what has to stay. Just disable the extensions, don't trash them.. If you run into problems doing this (not booting up anymore for example) , startup with 'shift' pressed to startup without any extensions so you can fix the problem. This method enables you to ditch options and OS addons freeing up Ram and resources (why waste Ram on network extensions if you are not using one for example...)
7. update your applications. (Quicktime, MRJ, explorer, etc....) to the latest versions. All updates can be tracked on www.versiontracker.com or via the apple website.
8. Install your software..
9. you're done ;)
It seems like it's a lot of work, but it isn't. It is a good idea to do a complete reïnstall of the machine, especially when you got it 2nd hand (as you don't know where it's been ;).. it will prevent you from having problems later on, related to the previous owner.. if you get really wild on this you can press the CUDA switch on the motherboard (small red button next to the CPU), remove the motherboard battery and wait for an hour... although this is overkill and should only be done when the system isn't booting anymore and booting from CD also isn't possible anymore.
You should be able to re-format the system and reïnstall the OS in about half an hour to an hour..but keep some time extra to troubleshoot if something goes wrong...