Sound in 7.1 issue

[quexos]

Got a PS3 and an HDTV connected by HDMI, so far so good.
But if I wanted to fully enjoy the 7.1 lossless sound, I'd have to get an audio system amplifier, so far so good.
But here is the question: how do I connect it ? you see, the only way to have 7.1 lossless sound is by HDMI and my PS3 has only 1 HDMI out which is used to send both sound and image to the HDTV.
The TV Itself has a L and R sound out, but that would only output stereo.
It also has a Digital sound out but it's only 1 socket, which means no separation of different sound channels.

So again, how do I get the best possible sound out from either TV or PS3 to a separate sound system ?