Just got a Sony Cdx-gt56ui cd player installed in my 03 g35 coupe with bose system. Getting sound from front door speakers and from rear nose subs but no sound from the rear side speakers. Is this a inevitable sacrafice with installing an aftermarket cd system or did best buy fuc up? thx

 

There's a lot of things they could have done - bypass the bose amp and use the four channel speaker-level output on front speakers and rear deck 6x9's, or they could have left the rear channels on the stereo as sub channels, so you're not getting any speaker-level output from them going to the rear speakers.

Honestly, you paid them to do it, take it back and ask them to explain.

 

Took it back to Best Buy and after jacking up the volume if u put your head beside the speaker you can hear faint audio. The tech thinks the speakers are going. Maybe I'll replace them. Thanks

 

Another possibility - is your headunit simply using the rear channel as a sub channel, or the EQ settings for the rear set as a low-pass filter (LPF)?

Make sure you're set to REAR-OUT, not SUB OUT, and rear bass enhance is OFF.

Check the manual here:
http://www.docs.sony.com/release/CDXGT56UI_EN_ES.pdf