Surround Sound dvd Package that pushes iPhone audio to all speakers?

Alright guys, figure I'd ask here because, well, we're all massive geeks and someone will probably be able to help.

My dad has a property he rents out in Europe and at the moment there is a rubbish cheap 5.1 surround sound dvd player linked to the telly. 

At the moment it only plays music out of all the speakers if a 5.1 movie is playing, anything else just comes out the front left and front right speakers - no optoin of playing the music across all the speakers. 90% of the time people just want to play music from an iPod/iPhone, and occasionally watch a film if the weather is terrible. There's a 2TB drive full of movies, and a WDTV player to get them on the telly.

Can anyone recommend a good (and loud) surround sound system, that can push out stereo iPod/iPhone music to all the speakers? If it has an iPod / iPhone dock even better. It'd be ok if it had a dvd/bluray player inside, but not essential as the WDTV can take care of the video. Volume is important as we like to party!

It's been almost 8 years since I bought one so I've literally no clue if they all do this now, or only certain brands / models. Any tips greatly recieved. Ideally we're looking to spend up to around £400.