aftermarket headunit

Hey all. First post here on the forum! Heard very good things about this place, so I figured it was a good idea to start here. Anyways, I quite recently purchased an after-market head unit (AVH-4200NEX). After getting this installed by Geek Squad, I began to notice what sounded like a...

I have a 2012 GMC Sierra w/o Bose. Soon I will be putting an aftermarket HU - either Pioneer or Alpine. I'm still debating because I have an iPhone 5 and they all don't work with the i5. Anyways, I'm taking on the challenge of making the audio system as factory looking/sounding as possible. I've...