Mumble audio quality issue

[Openblue]

Recently, other users have been commenting on how "low-quality" I sound on their end. This isn't the usual robotic crackling that comes from poor internet connection, nor is it a problem with the microphone because I've recorded myself both locally, using audacity, and over the internet, using vocaroo. Things are fine on Skype and Teamspeak too. Even loopback tests both local and server come up fine.

I've run the audio wizard multiple times, I've fiddled with several audio settings, including the compression and audio processing in mumble, and the microphone settings in windows. I've also followed the usual recommendations, such as forcing TCP, enabling QoS, and even a fresh install of mumble.

I'm at a complete loss. What would cause audio to be low quality only to other mumble users, and how can I fix it?