Getting audio from an HDMI cable?

[ffutures]

I've got a little Android box for watching iPlayer etc. on TV. It works fine on my small TV, but I'd decided it would be more useful connected to the big TV in my lounge. The snag is that its only output is HDMI, for picture and sound; what I really need is HDMI and a separate analogue sound output that I can connect to my home cinema amp. Are there any inexpensive adapters that can split off the audio signal but not mess with the picture? I can't seem to find anything like this on ebay without spending more than the iPlayer box cost.

The other possibility, of course, is to use the TV sound, but it's nowhere near as good as the amp can provide.

Anyone got any suggestions?