Ok, I just got off the phone. Turns out I actually bought them from Amazon, and have the receipt. They aren't covered by warranty because I changed out the cable to a Jena Labs. I would've had 1 month left on warranty if I kept them stock.
Denon parts does not carry the drivers. They want you to send in the phones to the repair shop + a check for $55 for evaluation, after which they will tell you Denon parts does not carry the drivers and you need to replace the entire unit for a "special price". That special price is $175.
So there you go: DENON does not support their products. I have had many phones over the years, and none have ever died. I am so glad I didn't purchase the ahd5000, or 7000! It is a shame - they sound really great; nice low bass, great comfort, incredible midrange clarity, but I will never buy headphones from Denon again. Companies like Grado and Ultrasone will get you back up and running again for a fair price. By the way - those Denon ear pads cost $129. Most companies charge $20-$30.
Good news is I get to start shopping again...