I heard the Duos with many different amps and to my ears the Audiopax Model 88 offered the most lifelike sound: gorgeous, rich tonality, tons of refined detail and very natural transients. These amps are amazingly fast.
My second choice would be the Viva Aurora monos followed by the Lamm ML 2.1.
My second choice would be the Viva Aurora monos followed by the Lamm ML 2.1.