That's a good point - while I understand the reason why h_h used a dialnorm of -31 (to avoid any attenuation being applied by the decoder), it does make it more difficult to use the track on a disc with multiple audio streams.

I spent quite a while adjusting the dialnorm values used for the three mixes on my DVD, and it's still not a perfect match, mainly I think because the '93 mix has a much greater dynamic range than the mono or Dolby Stereo mixes.

However, there is a program called VOBDNorm that you can use to change the dialnorm setting on a DVD's audio stream without encoding. I used it to make my original LD transfer louder.