I put one of those USB/SD/Aux/iPod ready head units in. Since my teenage daughters don't drive,yet, and I'm a frequent chauffeur, it was easier to let them play their music from the iPod, rather than put up with "radio roullette".
The sound from the import head is fine for my 1960's rock concert ears, certainly not audiophile, and they're inexpensive units. I was shocked at how everything played on it; Usb memory stick, SD card, iPod, CD, MP3 CD..you name it. Very cool.
ONE HUGE PROBLEM, however.
After buttoning it all up; head unit, amp A for rear speakers, bridged amp B for subwoofer, I had an alternator whine that wasn't present before. Since I had put a separate ground strap for the rear amp a few years ago, I KNEW it couldn't be a ground loop issue. After all, I had placed it myself
.
WELLLLL, anytime you have an alternator whine, CHECK your grounds, then re-check. Turns out my "pro"
sheet metal screw had loosened and wasn't providing a good clean ground. Did it the right way, with a bolt and lock washer, and the whine disappeared.
Point of the story... any "noise" in an audio install, check the grounds, just like the pros tell us. I'll listen better now
.