I tried it when I first got my L1 several years ago. I figured I really didn't need a Bose sub as My Z5500 Logitech had almost too much bass at times. I also did not buy the T1 mixer until later.
I hooked the Z5500 to the bass port of the L1. It worked but not well. As I recall, it sounded like it was not integrated with the system(which it wasn't).
I ordered the Bose sub and T1 mixer and never looked back. I ordered the compact when they came out, and now use it exclusively.
It might be that you can better integrate the Z5500 with the T1 than I did without it.
pa4X 76 ,Audya 76,Yamaha S970 , vArranger, Hammond SK1, Ketron SD40, Centerpoint Space Station, Bose compact