I dropped the 'CustomMainEngineSoundVolume' value to 235 ... I'll try bringing it down a bit more.
The only time I experience the crackling is during full boost at high speed (lots of engine noise (main and scram especially) + lots of wind noise (basically fast enough to start the heating process to the point where the skin starts glowing)).
Everything else plays clear at exactly those settings ... game sounds, all other orbiter sounds, mp3s, movies, etc ...
But, just to be on the safe side and rule it out, I'll reset the speaker connection, then disable the EQ when I get home from work this afternoon.
Failing that, I'll try normalizing the sound files themselves to a lower level just for my own curiosity. When it first happened, it really sounded to me like a couple of files that were internally too loud and were clipping ... hmmm, I wonder if OrbiterSound is having trouble with it (I can't think why it should, I'm just thinking out loud) because with high mach, full main throttle, and full scram throttle you'd have 3 very high level sounds trying to play simultaniously.
meh ... it's all good ... when it happens I just imagine it being something like the 'popcorn' sound you hear during a shuttle launch, push the throttle even harder, pull back on the stick and grin like a schoolboy copping his first feel. (I think my kids are now totally convince I'm crazy due to all the insane giggling coming from my room.)
:rofl: