I've bought 4 refurb Denon from eCost. All 4 were defective.
I sent a refurb Denon in for repair to the NJ factory once. It cost me $50 shipping. It came back DOA from the NJ factory.
Others have had better luck from A4L. But I would stay away from any other places.
I would buy an open box item from Amazon, Electronics Expo, One Call, etc, and get full new warranty. But personally I would have to stay away from all refurbs.
For example, Amazon was selling the Denon 3312 Open Box for $492. I would call around to other places and see if they have any open box items.