Darth Editous said:

I still swear I read somewhere that the AC3 mixes on DVDs were "broken" by the need to keep them sounding good on less-than-5.1 equipment.

I've heard allegations of that kind of thing before, but I've never been able to find a clear answer on exactly what the differences might be. It probably varies a lot with each film and by who is doing the remixing. There could be issues with the phase and timing of the surround channels that might theoretically affect the quality of a downmix, perhaps. But honestly, if they're so concerned about making the mixes ideal for being played on less than stellar equipment, why not create a 2.0 downmix especially for that purpose and make it the default track on the disc? That way people watching it through tv speakers or whatever can just put the disc in and watch with a mix idealised for them, and people with proper home theatre setups who actively care about this sort of thing can manually select the proper 5.1 track.

Some dvd's, such as recent Pixar releases, actually do this, and I think it's a great way to go. Compromising a mix just so it will sound better on lesser equipment owned by people who don't care about sound anyway, when there is absolutely no real need to do so, would be the height of foolishness.

I've heard that some some laserdisc 5.1 tracks have the surround channels set too high, because they forgot to recalibrate the mix for the smaller home environment. Still, that's easy to correct in the receiver setup (just don't forget to change it back later), and having the real theatrical mix is always a plus.