Just a word of thought now that this issue with Bose equipped cx5 keeps popping out.
When i help metalinvader with his Bose equipped cx5, we were faced with a serious subbass issue. There is no subbass sound emitting from the subwoofer at all, and this is made even more contusing because the ms8 indicated it detected fullrange signal from the source unit, which at that time was from the bose amp. Yet, no matter what we did, we just cant get good subbass.
Then i decided to use ipod as the main source, then lo and behold the subbass came back from the grave. Literally.
Since the bose dont use subbass, but a very big 9inch midbass upfront, this tells me they cut down the db level for bass section, perhaps somewhere below 50hz. So whenever someone try to steal the signal from the speaker (rear speaker supposedly received full signal) for subbass, the result is poor. Or maybe anyone who wanted to get subbass should grab the signal from the 9inch front midbass, i'm not sure.
The Bose system is pretty much like the JBL MS8, in terms of signal processing. Each speakers has a dedicated frequencies and eq level. The system is preset by Bose specifically for the Bose speakers, to achieve what Bose deemed correct sounding. So if anyone change the Bose speakers, your new speaker gets the crossover and eq set for the Bose speaker. This could be end in worse sounding audio.
My advise is if you have Bose audio, you either leave it alone or completely remove everything and start again. What you can do to improve things is to treat the doors. I like to add layers of foam sheets behind the door trim, acting as gap filler and cushion against the door metal skin. Sandwiched in between, leaving as little void as possible, and absorb unwanted high frequencies for optimum midbass. Adding dynamat is also not a bad idea, but it isn't necessary for cx5, as its service hole os already sealed. It is necessary once you add more oomph for the midbass though.
Another good trick is to place foam sheets on the outer door skin, right behind the speaker's magnet. This, believe it or not, absorbs backwave generated by the midbass. And foam sheets are cheap as chip, just make sure you use a good spray glue, like 3m foam glue.
