Up for sale here is this metal top cover from an Onkyo A-7 amplifier. This is in good condition with light to moderate wear. No hardware is included. This might fit the A-5 and A-10, but I don't know for sure. Please see my pictures for details and measurements.
US shipping and handling is $20, and international is $75. If you have any questions, please ask.
I have more Onkyo parts and other vintage electronics listed--feel free to take a look!