Are McIntosh dealers a good shop?, they print out a invoices. But when I had my MC275 serviced and brought it to a authorized tech, nobody ID me, I just showed them the receipt. serial number matched the amp and the date was still under warranty and they sent a copy to mac. If it was shipped people change addresses, people use others cards and accounts to pay, names change as it could have been a gift. All anyone needs is the receipt that matches the unit, that says when it was sold.
Unless when db contacted Technics they flagged his serial number. All he has to do is make a copy of the receipt and stick it in the box, let the service center contact Technics saying they have this unit, it's under warranty, and matched the unit sold xxx