No HDMI setup Option 1: If your TV support PCM output and have optical audio output you are good, you will get DPII/PCM signals, no receiver needed, just connect the optical to whatever audio system you have, you still need a 5.1 audio system with optical input.
Option 2: Now we can use HDMI cable for image and component/composite (red/white) for sound, both at the same time, it will give you DPII output, not sure if PCM can transfer with this setting though, you still need a 5.1 audio system with RCA input (red/white plugs).
You can get DPII or PCM sound formats through HDMI, but you need a receiver with at least 1 HDMI out / 1 HDMI in, in order to decode those formats, Wii U transfer the sound to your receiver, and the receiver transfer the image to your TV. It's the best audio setup available regards audio quality, but is the most expensive.
I thought nearly all TV's did not support PCM. I currently use option 1- HDMI to TV and TV has optical out to sound system.
The problem with that however is if I set the Wii U setting to surround it screws up the sound in Wii U games. Because of that I keep it set to stereo and a separate vWii surround setting would be better.
Option 2 is also going to have this problem I think.....you will have to be changing your sound settings whenever you want surround sound in Wii mode.
My sound system is pretty old but I just got a deal on a Logitech Z5500 system for $70...still no HDMI input on it though....
I updated my TV and save me from buying a receiver, my Samsung outputs PCM, it was a nice bonus for me, mine is UNF325000, serie 5, it's not the latest model.
I can confirm that the rear speakers works for me, Wii/GCN DPII games too, it's easily noticeable in Rogue Leader sound check, I also didn't know that TV could output PCM through optical, but this model does, in fact it leave you choose the output signal: PCM/Dolby Digital/DTS Neo 2:5