I would prefer to keep the OEM head unit because I like having the audio and Nav information on the i-MID screen, and I wanted to retain my factory XM tuner. It also eliminates the risk of theft of the stereo because no one steals OEM stereos. I am already running a set of RCAs straight from the head unit to the amp, the Premium head unit is unpowered with pre-amp output signals. It makes no difference if the shop had to splice RCA plugs to the factory wiring, just a little more extra work. I understand your preference with aftermarket stereos. I did all that back in college when factory stereos were not worth a damn. Factory stereos are far better than they were years ago. The poor equalization was caused by the factory amp, not the head unit, and that has been removed and replaced with the JL amp. I did choose the amp for compatibility with the head unit because I wanted it to work, and also because JL makes a good 5 channel amp which was small enough to fit under the seat for a nice installation. So I am glad the premium head unit worked perfectly with the JL amp without any line out converters, or any other issues. It is a great upgrade to do if you have the premium head unit. The standard stereo with the built-in 160-watt amp would need line out converters, or replace the stereo.