Is 250 Speaker Layout And Fader Issue

[neil0311]

I just took delivery of my IS 250 AWD with the factory premium sound system (not the Levinson) with dealer installed XM, and I'm puzzled. If I set the fader to all rear, I get a much lower volume and almost no bass. All I hear in the back is what sounds like mid-range. When I bring the fader back to the 50/50 rear/front, then I start to get volume and bass.

Can anyone tell me if this is consistent with their experience and also can someone describe the placement of the 13 speakers. Is there supposed to be a woofer in the back deck? I'm wondering if during installation of the XM unit the dealer might have screwed up something in the rear.

Any help would be appreciated. Thanks.