AV receiver single line output to two line input on sub woofer

SOURCE: Yamaha RX-V1200 subwoofer connection to Mirage BPS-150i subwoofer

just connect your subwoofer mono RCA to your amp sub single out rca connector. you do not need to megre all those 4terminals into one. in fact internal circuit of those 4rca are merging inside to one since the sub uses only a single amp. 4inputs was meant for sources with multiple sub out

SOURCE: I own a Yamaha RX-V461 and since making a few

You can reset the settings to factory defaults via the Advanced menu - it should be in your manual (I have RX-V465).
Do it from the standby mode.
Press the STANDBY button on front panel (not remote) together with STRAIGHT button on the front panel. Now you are in the Advanced Setup. Scroll to the INIT menu and select ALL.
Now you will have all settings in the default.

SOURCE: My RX-V995 receiver has no output to the

This is a tough question, if you paid a fair price for the unit then I would opt for an estimate. But! if the item was low priced then I think it is clear that a replacement would be a better way to go.

SOURCE: Yamaha Rx-V367 Subwoofer not working,

Have you looked at the manual?

The NEW thing doesn't work.

Does the subwoofer work for setup? That would certify the hardware and speaker definitions are ok.

The PC has the responsibility for defining and sending out something between headphone and full-blown 7.1 though the HDMI. Check your PC sound controls and the "Information on HDMI" section of the manual.

For the radio mode, probably the only analog stereo source you have, read up on the STRAIGHT decoding mode and Sound Field programs.