This one: https://www.amazon.com/dp/B0177DG71S/
Keep in mind I only did a few minutes of testing, so maybe we'll find a major flaw in using it. Personally, the only thing I need it for is to capture footage for streaming or just to show parts of games. As long as it doesn't totally suck, it's fine with me. I don't even care about lag, since I'll actually be playing on a CRT.
took a moment to realize what you're doing here. You're using the converter's HDMI passthrough input to increase compatibility, right ?
It's not a passthrough, it gets scaled too.
Just got mine and wanted to share my thoughts on it as a OSSC companion. I was hoping retrorgb would have missed something interesting but sadly not. I thought maybe it would support 240pX5 and retrorgb had too poor quality cables, but same connections as to my DVDO VP50 and no X5. I was hoping it would do 240p>480i transitions nicely (I know it should in RGB), but it doesn't support 480i passthrough at all (and the bob 480i transitions aren't that pretty either).
So my thoughts on the image quality. First it was ridiculously oversharpened, I turned my TV's sharpness to it's lowest value (way below neutral) to counteract the horrible ringing. The colors were way oversaturated, again happy my TV goes to below neutral values here to get it colors looking more natural. Still, the 240p test suit reveals that several of the brightest RGB shades are just gone, grayscale is fine though. It also seemingly dropped some frames (why?) and had some forced noise reduction creating image noise. Lag was also an issue (manual lag testing says between 1 and 2 frames). Somehow even with all those drawbacks it looked nicer than my TV's 480p handling. That says more about my TV than this box though.
As for this scaler as a OSSC companion, I wouldn't recommend it to anyone, except maybe if your TV doesn't support the OSSC even in 240pX2 and you just want something to hold you over until a new TV (though if a new TV is far away I'd get a XRGB-Mini over this wonky combo) or if you want to normalize OSSC's output for a picky capture card you want to use for web streaming.
That said they're also very cheap so if you're one of the people who spend a lot of money on stuff like this, might as well buy one in case you ever have a use for one.