Olaf van der Spek wrote:
A sub is okay, 5.1 might be okay too, the current system is 5.1 as well.
If a full 5.1 system is OK, then I would second the Energy Take 5.1 that Abula recommended paired with an AVR. It's not the best but very good sound for the money. For AVRs I've had good luck with Yamaha myself. If you can spend a little more, the RX-V477 has network control from your smartphone/web browser and audio streaming. It's a nice feature to have if it interests you. Being able to "fix" things on the receiver remotely is also high on the WAF.
Wouldn't ARC take care of returning the audio from the TV (PC & STB too) to the receiver?
ARC is from the TV to the receiver, mostly for audio from over the air. Some TVs will use ARC for audio from other HDMI inputs, but many won't. Don't count on it. TVs are also spotty on supporting audio out over optical and analog for non over the air sources.
What LG AIO do you have?
I don't remember the exact model and cannot check for a couple of months without some serious snow removal equipment. It is similar to the current LG BH6430P, just older. As I said it works, but its lack of inputs is quite limiting and we only have an HTPC, no STB there. I would only recommend it if your budget doesn't permit something better.
We used HDMI for video and analog for audio from the PC, toslink might be available on the motherboard.
HDMI makes things simple if you have a modern AVR. Toslink works as well, but then you have separate video. Having to only switch one input is very high on the WAF.
The height limit is about 135mm, most receivers appear to be higher, unfortunately.
If it's not out of your budget the Yamaha RX-S600 would fit the bill nicely. It is 111 mm high.