Re: Enable audio through HDMI on GT240
Can you please try "hw:3" instead of "plughw:3". Also, did you try plughw:9/hw:9? Any of the four devices might map to the HDMI port you're using.
You may also wish to run "alsamixer -c 1" and ensure nothing is muted.
"speakertest -c 2" might be the simplest test, rather than aplay.
If none of that works, pleas can you please copy and attach /proc/asound/card1/codec* and /proc/asound/card1/eld*.