I think the rca inputs rob the volume. Only way to fix is PAC harness

 

Update: I used the PAC harness and now its clearer and loud like normal. Sounds better then stock

 

I'm a car sterio installer and have been for 12 years. Nissan bose systems (or any Bose for that matter) have a VERY high preamp voltage off the stock headunit and the Bose amp is designed to work with it. If you buy a aftermarket CD player and add it to the Bose amp using Metra part number 70-7551 (as I'm certain you all did or something like it), then you MUST use a radio that has at least 4volt preouts to avoid this problem.... A workaround is to use Metra part number 70-7550 (non-amplified harness) and wire the speaker leads as normal, but then you will have the OPPOSITE problem it being TOO loud because you're running an amplified signal into the amp. If you decide to go that route you can work around that by using the 70-7551 with line out converters on the speaker leads (NOT the rca connections) on your lower powered aftermarket radio and adjusting the lineouts to a power level proper for the Bose amp. ...... PAC makes all kinds of interface adaptors... I'm fairly certain the one you guys were taking about is most likely a lineout converter......That is really it as far as all this is concerned.

 

What pac harness did you use and did you still use the metra 707551

 

This thread has beed idle for 5 years. Call a company called Crutchfield for free advice. Gl!

 

https://pac-audio.com/catalog/radio-...ment/roem-nis2

Shop around. Like $35-40. All that's needed for aftermarket-to-Blose system upgrade.