Well...
I too need to get some steam out of my system.
To OP, Zx10guy summed it up - If you are trying to work with your Bose products, you'll have many challenges. All of the above mentioned weaknesses of bose products add up to a disaster when trying to upgrade them.
All their products work best when used with their original equipment.
My suggestion is to sell the 161 / and center channel on craigslist and then do some research and get some decent speakers
[even budget, entry level speakers will do a better job than the 161's imo - as they will probably not even extend up to 150hz even at +-10db]. The Accousitmass bass module will be a waste of money / space --as you will never get desirable Bass frequencies. None of their products have a natural flat response.
Try to use their speakers with your own amp - and you'll get surges in certain frequencies "the size of Mount Everest" / dips in certain frequencies as deep as "the Grand Canyon".
I have had a few Bose products... some are OK
[especially when I was not a sound enthusiast, I was happy with them] and currently leasing a car with the factory Bose system in it:
2007-Infiniti G35s:
comes stock with the "Infiniti/Bose Studio on Wheels" system.
It is designed as a 2.1- stereo system - which has 24bit DAC, and a designed front soundstage. At first listen, it sounds OK- pleased with it- then after a while, I noticed sound depth, clarity, stereo imaging is very lacking!!! I tried everything to fix [mainly the clarity] ---
but MUD is all I'm getting. ---I'm returning the car after lease is over--- and this muddy Bose system is one of the reasons to why.
LOL-I'm actually using my headphones in the car- cuz I can't stand it's lack of Sq.
Anyways, end rant, ____________L
ps. I know that sound imaging is difficult to achieve in a car... but I've listened to Harman Kardon Logic 7 and Acura ELS stystems --- and they blow my system out of the water for Sq and imaging!!! BLEH-to-Bose!