Looks like the audiophiles over at the AVS forums weren't wrong about the New Xbox Experience killing some gamers' Xbox 360 audio (did you really doubt 'em?), because Microsoft has officially acknowledged the problem and promises a "solution" in the near future.
"We are aware that a handful of Xbox LIVE users are experiencing audio issues" a Microsoft rep informed Shacknews, promising that they're "diligently monitoring this issue and working towards a solution." According to numerous internet reports, after the NXE update was released a few weeks back, some Xbox 360 HDMI users lost all game audio.
Gaming without sound is no fun. Hopefully we can haz the NXE caused HDMI audio problems fixed soon.