Can I get some speaker / receiver advice?

[kidalot]

Hi there, I am a complete newb when it comes to home theater stuff.

I have a PS3, bit annoyed at the increasing number of blu-rays that have DTS-HD Master and no DD 5.1. I have a very basic crappy sound system that only decodes DD 5.1, any blu-rays with DD TrueHD still plays in DD5.1 but DTS-HD Master plays in 2.1, which is why I'm so annoyed with movies that don't have more audio tracks, surely they can fit it into a blu-ray?

My Goal: I want the ability of decoding DTS-HD Master and Dolby TrueHD cheapest solution

I have: Extremely cheap and old 5.1 sound package (Logic3). The 5 speakers are connected to sub woofer and the sub woofer is connected to the receiver via 9 pin DIN.

What I want to know: Can I get away with just buying a receiver or would I need another sub. I've looked at a few receivers and can't see away of connecting my current equipment to it.

I'm not looking to spend much, possibly £300 overall, I just want to know what I have need to save up for.

Any help appreciated, thank you.