I just installed a 4100NEX in my Mazda CX-5 with an amp/Subwoofer combo. I've had the amp/Subwoofer for about 7 years, and have installed it in a couple other vehicles with no issues.

My issue is the bass when using Bluetooth or connected through Android Auto is underpowered or feels underwhelming. However, when I have a CD in the deck the bass sounds good and booms like normal. This bass issue seems like it is not just limited to the subwoofer, but it is the most obvious with the subwoofer.

the only thing I can think of is to check your eq settings. if im not mistaken pioneer radios let you have a different eq setting for each source.