I'm not a 100% sure... I bought all the parts and then had a shop install it...
I did purchase this so I was under the assumption that the Bose stuff was still being used: PAC ROEM-NIS2 System Interface Kit to Replace Factory Radio and ... https://www.amazon.com/dp/B000CE9OY2/ref=cm_sw_r_sms_awdb_t1_kewKBbKMG7D5B
The installer said he wasn't needed, but I didn't get it back, so I'm not sure if it was installed or if they just kept it.
If you have the bose system you can get a small amplifier which will restore order to your audio system. It's specifically for aftermarket head units fitted to nissans with a factory bose system.
Granted, I'm not a massive audiophile but to me it sounds good enough
https://www.amazon.com/PAC-ROEM-NIS2-Interface-Integrate-Amplifiers/dp/B000CE9OY2
I am speaking from personal experience on my own car and I'm not sure if it'll pertain at all to your situation so take it however you want.
I own a 2006 G35 with factory bose amp and if I did not use the correct interface kit and spliced the headunit cables directly to the factory audio interface, i would experience the same exact symptoms you did. This was because on my car the bose amp needed to havea the correct signal supplied to which was only possible with this interface kit: https://www.amazon.com/PAC-ROEM-NIS2-Interface-Integrate-Amplifiers/dp/B000CE9OY2
again this is for my car and I dont know if you have a factory amp or anything but maybe its something you can look into
Best Buy did not sell me that adapter, unfortunately.
While researching the LP6-4 I stumbled upon this: https://www.amazon.com/PAC-ROEM-NIS2-Interface-Integrate-Amplifiers/dp/B000CE9OY2
$20 cheaper and addresses the issue of connecting to Bose amps in a Nissan. Just ordered it - will update after I hook it up.
I have Bose, and you need the PAC ROEM NIS2 wiring harness. Makes life simple. Nothing extra, just a wiring harness that you should do anyways instead of cutting into the cars wiring harness. It says its for like year 2000 cars from nissan, but its a lie. It still works just as great on my 05.
You need a wiring harness like this one: https://www.amazon.com/PAC-ROEM-NIS2-Interface-Integrate-Amplifiers/dp/B000CE9OY2
and a headphonejack to rca Splitter like this https://www.amazon.de/gp/product/B007K8RVHU/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
You can wire everything together and it will work with the bose amp. You can also plug in an aftermarket amp.
assuming by kit you mean it comes with the adapter that has RCA connectors? If you have an offbrand radio or it doesn't sound right after install you might need the PAC-ROEM NIS2
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https://www.amazon.com/PAC-ROEM-NIS2-Interface-Integrate-Amplifiers/dp/B000CE9OY2