XSquawkBox 2.1 is a minor feature update to implement the new radio effects as used in the standalone AFV client and xPilot/vPilot.
It also fixes the bug where the Enable Radio Effects checkbox in Audio Setup didn’t actually do anything (Radio effects were enabled always).
XSquawkBox 2.1 can be downloaded at the download page.
Update: Because I’m getting too many reports of this, do NOT run the AFV standalone client alongside XSB 2.0 or newer. You don’t need it – AFV support is fully integrated. No support or consideration will be given for issues caused by trying to run both side by side.