I got a problem with three DOS-Games that come with a CD with game on track 1 and music on the following audio tracks.
Games: Fantasy General, DSA Series 2 and 3 (German Series Das Schwarze Auge, english Realms of Arkania)
Tried two different PCs : 1. WIN 7/ 64bit, 2. WIN XP 32bit, SP3 ;
Onboard Sound; DosBox 0.74; Cue/Bin Image created with Ashampoo 12 (latest).

All three games run perfectly on both systems with gameplay, music and sound effects when playing using the inserted cd.
When using the image file - I tried
imgmount G "D:\DOSGAMES\fg_img\fg.cue" -t iso
imgmount G "D:\DOSGAMES\fg_img\fg.cue" -t cdrom,
gameplay and sound effects are working, I hear the music somewhat fainter, but its overlayed by a constant crackle similar to a badly shielded cable, somewhat sharper than a 50Hz current sound and not as clean. Were it not on both systems, I would actually take it for a hardware failure like transmission from a fan motor.
I tried various settings of the dosbox.conf file :
cycles=auto / fixed 12000
blocksize=1024 / 512
prebuffer=20 / 10
irq=5/ 7 / 10
dma=1 /5
Those changes had no effect (of course in spite of running the games' sound setup again after changes).
Other games, for exampleTES2-Daggerfall, run perfectly using a cd-image-file.
I would appreciate hints on how to fix this. Dxdiag.txt of PC 1 attached. - Many thanks.