Hey everyone, new to the forums. I've spent the better part of the morning reading numerous forums and trying to find my answers but to no avail.

I have a 2008 C300 with the Harman Kardon sound system. One of the rear deck speakers is blown and rumbles when any kind of base is playing. I'm not an audio guy, but a friend enjoys doing this kind of work so I plan to help him when we're working on the system.

Does anyone know if I can still get ahold of an OEM replacement HK Sub? Is it worth going OEM HK? Are there any other direct replacements that are recommended?

My friend suggested disconnecting the HK Sub and adding a custom/aftermarket sub and box in the trunk. I'm not opposed to that, but he warned the mid-range could end up being lacking.

If you were in my position, what would you guys think to do first?

Thanks for any assistance!