Was talking to Jon after Marc left. One of the things he said was that he didn't consider the Ayon Orthos II at 400/channel to sound that much different to my vintage Accuphase monos. When here, he expressed a preference for the Accuphase amps over the Ayons.
The Accuphase M-60s are greater than half Kilowatt capable into the Duetta. So a tad more powerful.
However, the difference in sound quality between the Austria Analogue 211s and the Accuphase is quite marked. I actually think the 211s have better bass. It is faster and more dynamic. The Accuphase do sound cleaner, however, and will play louder, but not by a massive amount to be quite frank about it.
The truth is it is an exponential scale and the increase in volume over dumping an extra 400 Watts into a Duetta is actually not that pronounced. The speaker will NOT play as loud as a pair of Wilsons, say, and the extra power just gets "drunk" by the speaker.
Anyway, Marc was offered the chance to hear the Accuphase but declined. He didn't get back home until 1:30 am so that is understandable.
Me? The truth is I haven't listened to the Accuphase for a few months now. However, summer is on its way so they'll be back in soon. And I know I'll wonder why I didn't plug them back in sooner.
Then I'll swap the 211s back in and wonder why I didn't do that earlier.
Both solutions have their own merits and disadvantges with the Duetta. It is a model that will thrive off tube amps and the same cannot be said for the rest of the full range riibbon designs.
Are really expensive amps necessary? If it makes you feel better you spent a shed load of money on them, then yes. Otherwise no. Finding a good match, if you can hear through price, is a much better option.
The 211s retail is around £7-8K, if you could buy them, but I don't think you can anymore.
I've got a £200 2nd hand Apart Champ One 600W class G/H amp that sounds surprisingly OK driving the Interstella. Really - it does a good job.