I honestly didn't research the active bass speaker system as much as I should have mostly because the door speakers worked, and worked well, after wiring in the amp. The bits and pieces I found on benzworld.org is that they driven off the front dash speakers but have a "black box" somewhere in the system. Here's the only wiring diagram I could find.
I didn't do any fancy wiring, just carefully clipped and connected the 4 channel amp like I only had front and rear speakers.
If I could easily find the bass speaker wiring, I would probably do what you said, but I don't think I'll be able to quickly/easily find them. I could post on benzworld about that and see what others have done.
Here's the only schematic I could find. If you can't read it, the bass door speakers are at the very bottom corners with the "black box" center bottom.
With the amp sensitivity turned down, the active bass added a lot. But with it turned up, it got ugly at high volume...think Evanescence Bring Me to Life...beautiful, clean, clear and bright voice but shuddering bass that wasn't right. Have to find a balance.
