Help! Hearing my own voice during calls on 6.5 ROMs

[gravitron]

Every 6.5 ROM (several Energy and both Mighty) I flashed to gives me a bizarre issue: I can hear my own voice from the earpiece during voice calls and callers tell me I sound like I'm on a speaker phone.

I flashed back to stock to bring the phone back to TELUS, thinking it was a hardware problem and... everything's normal! (OK, the ROM sucks compared to 6.5, but the voice issues have disappeared).

Any ideas?!?!?

Thanks for any insight.

Phil