I checked some other releases, and error is present in all. But it is actually not STE DMA audio what makes that knacking, but PDG audio. I was confused, because only init screen music goes via STE ADMA, after it effects in game are done via PSG, even if it is sample playback. Very strange. Probably the reason is that samplerate of those effects is not good for STE ADMA ? But why they did not make separated version with proper rate samples for STE ?
Anyway, code is really not enough quality, and I found a way to remove those knacks. Will put soon hard disk and floppy disk versions on my site, need yet to solve some other problems - like crashing on Falcon - bad stack handling in ADMA detection routine.
Famous Schrodinger's cat hypothetical experiment says that cat is dead or alive until we open box and see condition of poor animal, which deserved better logic. Cat is always in some certain state - regardless from is observer able or not to see what the state is.