Having just purchased Aletha's, I have not had a lot of listening time with them yet, but I use a Bryston 4B-ST. The person that I bought them from also used a 4B-ST. So far, I'm having excellent results. Imaging and soundstage are wide and deep. Bass is strong and tight as would be expected with the Dunlavy/Bryston combo. I don't know about the impedance issue but I'd second Drtmth58 in that a high current amp is always a good thing. I've also heard the Aletha's with a McCormack (sp?) amp, albeit different source and room, with excellent results.
