Seems we need to work further to ID the component at fault:
1. how far your turntable from your left speaker? try to isolate turntable or simply disconnect and take away from rig and see if problem remains
2. what source you're normally running when the pop(s) occur?
3. have you tried running this receiver 2ch only with video sources disconnected and unpowered or the same with audio sources disconnected and unpowered?
4. have you tried running system with no subwoofer?
5. do you connect your main speakers to subwoofer or receiver? have you tried connecting to subwoofer instead if you didn't?
6. how far your turntable from subwoofer?
1. how far your turntable from your left speaker? try to isolate turntable or simply disconnect and take away from rig and see if problem remains
2. what source you're normally running when the pop(s) occur?
3. have you tried running this receiver 2ch only with video sources disconnected and unpowered or the same with audio sources disconnected and unpowered?
4. have you tried running system with no subwoofer?
5. do you connect your main speakers to subwoofer or receiver? have you tried connecting to subwoofer instead if you didn't?
6. how far your turntable from subwoofer?