New stereo deck... speakers and/or sub next?
 

Just had a new stereo deck installed in my 2004 venture. A Sony XAV-64BT. It's a nice deck and meets my needs but I want better quality sound. Should I be replacing speakers, if so, is it just a matter of buying all new speakers and replacing the existing ones while using the same wiring? Should I be adding a sub? Any stereo advice would be appreciated. I basically listen to rock and heavy metal.

I would replace the speakers first!

I have a 2005 Silverado extended cab. I started with a pioneer deck and just got lucky when a friend was selling the custom enclosure for under the rear seat for subs, with two JL 12's and a 600w amp. So I bought it and installed it and blew out the factory speakers within a few weeks.

I ended up getting JL's to match the subs and I couldnt be happier!!