Sorry, disagree with that (soz) I changed the speakers in the GS, not much difference, changed the drive unit (head) and it came alive. For sure the its a 'Chicken and Egg' thing.......you cant have one without the other but the head unit needs power to be effective.
General wisdom is always to change the speakers first - OEM quality are usually terrible - paper cones, small magnets etc. Matt is right in that they'll never make a significant difference or make poor sound quality fromthe head unit great, but there's also no point in changing the head unit for something of higher quality/more powerful if the OEM speakers can't handle it. Speakers are the direct interface between the sounds being produced and your ears, so are extremely important. Next is the head unit, especially if it has better controls over the sound output, then amplifiers to help boost the output. People also generally forget about the cables - a fortune is spent on hardware and the crappy cables remain! As we've heard from various 4200 owners, they've changed their speakers and seen reasonable results, but the info centre is ancient technology and basically rubbish in producing a decent sound output. One of the reasons I chose a 3200 over a 4200!
