I ran upon an Ampeg B500DR for sale. A friend of mine has it, bought it new, and is looking to sell it for some quick cash. He has played the amp very seldomly. I really don't need it, but, if it will help him out, I may pick it up. What are some of the pros and cons on the amp? What's a good price for this amp in mint condition? I know it is digital and I also know it was discontinued a while back. Thanks for your help and input.