Hi. I have a Kenwood Kdc-261u unit in mine. I got this one because it was on offer at halfords and the adapter to connect it to the steering wheel controls was easy to get hold of. This unit has aux in and usb connectivity. I can control my iPod through the unit
If it's better sound you are looking for then you are probably best getting new speakers all round. The factory ones are mediocre at best. They dont have a great range. Hope this helps