There is already a separate sound channel for the music (thank the gods). All other sounds are in the same channel. What you want would be another channel for the ambient sounds, leaving the 'normal' sounds of nearby mobs in the existing channel. That way you could turn down the music and ambient sounds and keep the sounds of mobs you are fighting.
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It's bad luck to be superstitious . . .Palta e decata, nan nec ilne matala.
When one goes on a journey it is not the scenery that changes, but the traveller