The 300 series ML’s are high biased class A/B, B after the bias runs out, they are not pure Class A.
Looking at the heatsinks I say about 20-30w Class A bias max, as Stereophile also said they weren’t too hot to touch, even after 1 hour pre-conditioning at 1/3rd power.
If they were pure Class A they’d be the size of a very large coffee table with heatsinks big enough to warm the whole neighborhood.
Stereophile full power tests on the No.334 are at 1% THD!!!.
8ohm = 139.9w
4ohm = 243w
2ohm = 430w
Bottom of the page measurement chart
http://www.stereophile.com/content/mark-levinson-no334-power-amplifier-measurements-page-3#toJJo0Xxp6m0aqe4.97 Cheers George