Oh, crap! Also, you need to know that any conversion you do is going to break your image anyway. The SNES spits out 240p, which modern HDTVs don't understand and just treat as 480i. The resulting image physically works, but is far blockier than 240p on an SDTV is. Doin a quick look on ebay, the HDMI adapters convert to 720p, which if possible it would be nice to avoid. Also, some HD scalers completely choke on 240p, resulting in half the image being pushed off the screen and odd side-effects like flashing. Any scaler inside of an HDMI converter box may choke on 240p in the same fashion.
All I'm saying is that on top of finding the right cables and adapters, of the correct video format type, you'll also need a healthy dose of luck for it all to even work.