Interesting, I didn't know he was a singer but there are albums on YouTube so I had a quick (too quick?) sample - and I don't really like his singing voice. It seems to come from the back of his mouth, is a bit flat and warbles.
Perhaps if I listened properly to a few songs I'd find something but even though it's a jazzy/crooner sound I usually enjoy I suspect he is really just an actor who sings a bit.
Sorry.
I have always depended on the kindness of Strangers - and the bastards let me down!

Is there no one else who respects him as a singer? Is there no one on this board who even has any of his recordings?