Checking in with the hive mind out there, what is the best available software for isolating the music channel from a DVD or Blu-Ray disc and ripping it for macintosh?
Does anyone have any recommendations?

There is no "music channel" on a DVD except in very particular cases where the "isolated score" is a bonus feature. What you're probably thinking of is grabbing the 5.1 surround mix from a DVD and cancelling out as many sound effects as you can. Ripping the file to your computer is the easy part. Removing the SFX is very laborious and oftentimes will amount to something that's not really enjoyable to listen to.

There is no "music channel" on a DVD except in very particular cases where the "isolated score" is a bonus feature. What you're probably thinking of is grabbing the 5.1 surround mix from a DVD and cancelling out as many sound effects as you can. Ripping the file to your computer is the easy part. Removing the SFX is very laborious and oftentimes will amount to something that's not really enjoyable to listen to.

Well then how exactly would you go about removing the SFX (and voices)? I know there isn't a solid fix to that which will work for everything in existence but there also doesn't seem to be any general consensus either. I've tried it myself and didn't really know where to begin, so naturally I go to look it up and find nothing, no guides or even tips on how to do it properly. I guess if you're already an audio guy who knows their way around Audacity and everything then it's a piece of cake, but to people like me who want to try but don't know the process, it's very frustrating.

Voices and many of the pedestrian SFX are generally situated in the center/3rd channel. That doesn't mean they won't bleed through occasionally to the fronts (1st and 2nd channel) or even the rears (5th and 6th). Delete the 4th channel (LFE) outright as it's just extra bass information you don't need in a stereo mix.

If you're interested in doing anywhere near a good job you'll also need to pay attention to what effects are mixed in the fronts but not the rears. Sometimes you can remove a portion of the fronts and get the music (relatively) clean in the back, or vice versa. Use the envelope tool to smooth out the volume. Be prepared to make some editorial decisions. Get ready to sink a lot of hours into something that might not turn out the way you want it to.

Apart from that I'm not sure what I can say that could make the whole thing easier for you. I've been doing this sort of thing (with mixed results) for quite a few years now and I'm still figuring out little tricks I can do to bring out the best track I can (even if it doesn't 100% mirror how the music is edited). It's one of those things where you have to do a lot of hands-on to be able to produce something worthwhile to both yourself and others. Sometimes the re-recording mixer will cut you a break and leave the music isolated in the rears or something for a large chunk of the film's runtime, but it's rare.

Hm. Thanks for the informative reply. I know about the channels and all, believe me I toyed with them a lot. In the mix I'm trying to work with the voices and most of the sound effects bleed through to every other channel which makes it almost impossible to get good results from my experience, I may be missing something but from what I understand mixes like this are pretty much guaranteed for bad results. I even tried several vocal removal tools and none of them helped at all.

If that's the way the audio is mixed, then that's that. There's not much you can do about it unless you want to get into "spectral editing", which is a whole 'nother ballgame (and much harder to get good results from).

Generally I've found that the lower-budget stuff (cartoons, direct-to-DVD movies, tv shows, etc.) will be the material that has the most potential for "ripping" music cleanly.