From the card, it goes: S-Video cable, s-video to RCA converter, RCA cable, coupler, RCA cable, TV (I decided to snake it around the room, so I needed a lot of cable.) ...

BP0028 RCA coupler male to male, connects 2 male to male RCA cables. The coupler is for a single connection, hence 2 audio cables would need 2 couplers, one for the left wire one for the right.

BP0025 is a RCA coupler female to female, connects 2 male to male RCA cables. The coupler is for a single connection, hence 2 audio cables would need 2 couplers, one for the left wire one for the ...

Most cable head ends are replete with F81 coax couplers with no ill effects and that's RF you're talking about. The bigger issue the dfedders mentioned was impedance mismatch.