Well, my timing is a little off, but I've decided that I'm going to go ahead and start setting up some tests. I've created a 20 GB virtual disk for my root drive and a 20 GB virtual disk for my home directory. If I manage to do everything right, I can re-use said home directory (and the kernel configuration) across all the distributions that I test.
First one I'm working with is actually a variant on Gentoo called Funtoo. I'm going to use this as a basis to judge other distributions going forward, so right now I'm doing a full KDE install and installing the granddaddy of all necessary Linux audio programs, Ardour. As this is Gentoo based, everything requires compiling and installing, a trade off in hopes of better stability and customization, so it will take some time.
After that, there'll be plenty of configurations I need to do for my desktop environment (DE), as well as just about everything else. This will take a decent chunk of time, probably in the three week to month period. I still don't have my memory upgraded, so my system's definitely being a hair more finicky than normal. I think that after this, I'll probably do an XFCE install too and choose which one to use for audio. Part of the beauty of Linux is that I can easily switch DEs whenever I want. I think that what may be the best choice is to have a dedicated DE for audio (XFCE or something else lightweight) and one for personal use (KDE or something a little more bloated).
Much of my configuration needs I remember, but some of them I do not, and enough of them have changed in the past four years that I will need a retooling to a good degree. I'll be doing my best to keep this updated as I go along, but for now, I'm watching a whole lot of emergeing on a virtual machine.