connects2 ipod help

hopefully someone can help me out with this.

I bought a connects2 ipod kit to fit to my 10 plate roomster with the dance head unit. The head unit had the aux connection in the back i disconnected it and plugged in the connects2. It worked fine and the head unit recognised it but the sound is as though it is far away. I know the system is not faulty because i tried it in a passat with the rcd300 head unit and it sounded fine. It must be something to do with the head unit any suggestions would be greatly appreciated.

cheers in advance