Over the last few weeks, I've had some trouble with my mach 460 system and over the last 6 months my HU has been slowly dying. I think i'm going to take this as a sign to upgrade the system even though i hate to spend the money on this instead of saving for a supercharger. Back to the point, I've been looking at HU's and i think i want to stay relatively cheap while still having a nice system. I'm looking at a Pioneer 5.8" touch and a Boss flip out 7" touch (some brand walmart sells). Now pioneer sells a high speed USB for Ipod/Iphones but i heard the user interface with it is still screwy. The Boss system also has a USB port on the faceplate, but i've heard its very tempermental and doesn't always work, perhaps because they don't sell their own usb cable designed to work with their system. Now both systems have Aux inputs via a 3.5 mm jack. My question is will the audio sound the same whether or not it comes through the high speed USB or the Aux input? I like the Aux input since i retain functionality of my Iphone, meaning i dont have to go through the HU to access music and i can just play playlists straight from the phone.