I tried my Switch into OSSC Pro just now and I’m getting audio from AV4 as I should, so it seems to me this problem of “no audio on AV4 with a RT5X+OSSC Pro combo” is either a quirk of the RT5X or some combination of things.
As for why I’m adding the RT5X, I needed all of the following or it just wouldn’t be worth it:
- Low lag: The low lag of the RT5X was made even lower by porting over features from the RT4K.
- Seamless 240p/480i switching: The RT5X handles this without a problem in 1080p Over. On the OSSC Pro, I still drop on Scaler Mode + Scaling algorithm: Integer (overscan). It’s fine without the overscan, but I can’t go back to that anymore.
- HDR injection (a.k.a. “fake HDR”): My 1080p TV doesn’t seem to support HDR from the OSSC Pro, and from what I see on the RT4K wiki, even the RT4K doesn’t have HDR injection. Looks good to me and plays nice with my capture card.
Plus according to this tweet, I still get 4:4:4 with the RT5X in all 1080p modes for PS1 (not so for the Saturn). And easy composite and s-video in for the OSSC Pro. I couldn’t do my fine-tuning on anything but the OSSC Pro though.