Actually, it is quite good. The only thing I found puzzling was the so-called 'classic music' - it is nowhere near either Roland General Midi or Roland-MT32. The remastered sound track is much closer to the original. I still have both the English CD version of DotT released at the time plus Roland's SC-55, SCD-7, and MT-32 in hardware. (Apparently, the music at the time was done with Roland stuff, which is why playback with Roland stuff also sounds best.)
However, you can easily check this for yourself. Unpack the tentac.le file with the Double Fine Explorer (they have since released an update for DotT Remastered) - in the 'classic\en' subdirectory you will find the files necessary to run DOTT under ScummVM. However, Double Fine have unfortunately forgotten a vital file - the one that includes General Midi and MT-32 / CM-32L music! This means that the music in ScummVM is only Adlib / SoundBlaster FM. But this problem can be solved easily. Just get the Roland / General Midi update released for the floppy version at the time and copy the file tentacle.002 from that update to the classic\en directory.
You can for example get it here:
http://www.patches-scrolls.de/patch/2587/7/27445. Then unpack the file and run it under DOSBOX and install it to any directory. Then copy the tentacle.002 file. Do not copy the tentacle.000 as well because that is only for the floppy version - the CD version already had General Midi / Roland support. The two IMS files are only for DOS / DOSBOX.
Now you will see that even with the much scolded Windows Software Synthesizer (tell ScummVM to use General Midi and then select the Microsoft Software Synthesizer) the music sounds much better than with the so-called classic music provided by Double Fine and much closer to the remastered music. (Alright, the hardware versions I have sound much better still but at least the Microsoft Software Synthesizer is enough to get my point across... By the way, MT-32 also works provided that you disable General Midi in ScummVM and select MT-32 instead.)
Apart from that, there were questions in this forum about whether the monster.sou file (sounds) supplied by Double Fine had in any way been tampered with. The file size of the one that came with my CD version released at the time is 262,662 KB.