I had both the 6000A and the a11 Tribute for a short time and didn't like either. The Audiolab I found cold, clinical and uninvolving and the black finish had a weird residue which never came off however much you tried to wipe it off. The a11 Tribute I was maybe a little hasty to dismiss but it's volume control was awful - I could only get barely audible sound with the volume set to about 25 and this really put me off. "It's supposed to be like that", was the response from Sevenoaks, who said this is how digital volume control works.
My vote would be for the Denon pma 800ne. This after a bit of a warm up out of the box sounds terrific to my ears - punchy yet even-handed, delicate sounding when required but capable of big dynamic swells. It's a lovely solid old school build, looks nice in silver, and has a wonderful weighty feeling volume knob which moves physically using the remote. Source direct, physical tone controls and the ability to isolate the digital circuits when using an analog source rounds off and excellent package.