a.wayne,
I only just now saw your post. [Merry Christmas!]
Seeing as I accepted responsibility for not double boxing it in the first place, I also accepted the buyer's request (demand?) that I pay for return shipping. The buyer double boxed it and insured it at my request through the carrier - $34 - which I also paid for.
After my refund, I am out approximately $160 for shipping and insurance in both directions. The buyer was out time and anxiety, but he got a full refund. I could just toss the amp, keep it for salvage/education, or send it to SimAudio for repairs. My intention is to have SimAudio repair the shipping related damages and ship the amp back to me. Then, I will sell it with appropriate disclosure.