The big issue is. The Bose system is designed to work with the Bose Media center.
Manual and information.
First questions, answer = No.
The RCA-port on the SUB are OUTPUTS for the BOSS speakers. Not Inputs.
Second questions, answer = Maybe…?
There is a small change. Make it work… but it’s all test and try and DIY. High change of breaking something. You would have to figure out what ports/port, in the 9-pin cable the sub/bass signal goes. Probably would also need EQ that it will not play any other FR-range.
And not sure is it even a good idea to use speaker cables from amps as signal.
So i would say. It’s a waist of time.