Pass Labs X5

I believe the X series amps, which are class A/AB, are biased in full class A to 20% and then switch to class AB. For the X5, that means 25W into 8 ohms Class A and thereafter up to 125W into 8 ohms Class AB.

I believe Nelson Pass used this same percentage on the Threshold S series amps as well.

I know I’m resurrecting a 13 year old thread, but just felt like I had to correct the assumptions in here for the record, since I own an X5. The X5 idles at 200w and provides 40w x 5 of Class A power per channel before crossing over to AB.

It is a legitimate space heater, brutal in the summer, and has necessitated the addition of a mini-split AC unit just for my Stereo/HT listening space.

In fact class A amp maximum theoretical efficiency can achieve is 50%.