The solid rear panel is normal, and doesn't help the low-range sound, probably making it unnecessarily boomy. If you are like me, I thought the sound was boomy, and muffled, even at low volume. There are certainly better $1200 factory sound systems. Even the $300 Jeep Infinity system I had was superior. Nonetheless, you can adjust the sound so that it isn't boomy, and sounds pretty good. Create a Memory 1 setting using the DSP. Turn off all room size and echo, and start the system flat, then adjust to your preference. I wouldn't use the room size and echo...to fake for me. My settings are + almost all the way up on 80, flat on the next 2 settings, +2 on the next two, and then I go up to + almost all the way as you approzch the high frequencies. It just takes alot of customization to sound good. It took me a good month before I found settings that rid the stereo of the horrible sound it was delivered with.