The one shown on Ebay is a January 1977 model, so its a later one, rather than an early one from '75, not that there is any difference otherwise between them. Technically speaking, the AU-20000 was introduced as part of the elite 'Definition Series' models which include the BA-3000, CA-3000, and of course, the mighty BA-5000 - all distinguished by the block diagrams on the claret- colored top cover and the glowing green meters. In fact, you can think of the AU-20000 as simply a combination BA-3000/CA-3000.
The AU-11000/AU-9900 was introduced later as the 'Professional Series', and the AU-20000 (according to what I see from my catalogs) was then listed alongside the 11000 & 9900 as a Professional Series model- along with the TU-9900 Tuner.
I had an AU-20000 for a while, and Yes its a great model, but I sold it to offset the cost of buying the two BA-5000's I have now.
The Ebay seller couldve mentioned in his ad that the unit originally came from outside the U.S. since it has a 220V sticker in the back :huge:
B/F
