Class A amplifier choice, need suggestions

What is your favorite class A amp and why? There are many here on Audiogon... Levinson, Krell, Pass Labs, Plinius and an occaisional Accuphase A50V. I am driving Proac Response 3.8s (88dB efficiency). I recently auditioned a Pass Aleph 5 and was stunned by the presentation at only 60wpc.

Your input is much appreciated!