Quietest amp you ever owned ?

A few years ago I had the little Antique Sound Labs MG SI 15 DT integrated and was impressed how quiet it was; in other words with the amp on and no music playing it was dead quiet when I put my ear right up to the drivers on the speaker. I am curious what other amps out there are as dead quiet since most amps have a slight hum or hiss that can be heard when music is not playing. At the time I was using Coincident Conquest speakers which are pretty efficient.