Did you tell him it was new? If its 'never been used', that means it is new, right? Either way, you can not justify the condition of that amp, new or used - and they way you and your friend are saying you can't offer him a refund. Its going to get back to the both of you. So, I suggest you call up your friend, and tell him this deal isn't happening, hack out the 8 grand, and pay this guy back.