Yes me too (X-Fi card, it supports up to 128 channels on gaming mode), i think its a sound volume on individual effects, some get too lound and others so low to the point of being muted, it happens randomly, after initial login everything is fine and working, and after a while or doing pve suddenly i cant hear the reain or footsteps, or attaks or the wind, some are very hard to even detect they are missing if you dont know the area, im trying to figure out whats causing it, settings, engine or card. Tested on all mixing buffer sizes and medium to high sound quality.