from the wiki:

Audio tracks

For more information about how to use the PC CD audio tracks with ScummVM, see the user documentation.

It's also worth noting that the CD intro never matched up quite as well with the music as the earlier floppy versions did.
This is noticeable both with the sparkles on the Lucasfilm logo and the appearance of the Monkey Island logo.
In ScummVM 2.6.0 the music is also likely to get cut off at the end of the Monkey Island theme,
when the intro reaches the lookout scene, because ScummVM matches the timing of the original game much more closely.
(It appears that the intro was timed with the assumption that there is no silence at all at the start of the track.)

To offset this, 2.6.0 also adds two sliders: "Intro Adjust", which specifies at which point the intro music should start playing,
and "Outlook Adjust", which specifies by how much the start of the outlook music should be adjusted.
For me, +1.14 and +0.40 respectively produce good results. 
