The nice thing about the AU-X901 is that it's an international amp, USA voltage, easier to get in USA, between $450 to $600 for a minty one, and it does sounds really good.
The X701 sells for a couple hundred cheaper and, from what I've been told by a fellow who had both, sounds identical. Only real difference: 100W vrs the X901's 130W. 'Source Direct' mode sounds wonderful. Loudness too. and MM/MC!
The X701/X901 are 'earlier' export alphas. 1987. They are internationally desired, especially in Germany. And the prices are much higher in Europe too.
It's also much easier to find a X701 than a X901. It's 'kind of like'... the folks who have the X901 aren't selling them. It's a really nice amp.
Happy Hunting. Wait for a 'minty' one, which ever one you get. Good Luck!