Levinson 436 vs 336

Both of these amps have the same power specs - but I'm curious regarding the sonic signatures. Some seem to prefer the older 3xx series of Levinson. I'm trying to understand what those differences are.

the newer amps are sized for rack mounting. the heat sinks are smaller and they use fans for cooling. older amps(I have a 332) have big heat sinks and they weigh much more than the new "improved" amps. older amps like mine also have two sets of binding posts which make bi-wiring easier.
I've got a pair of 436's and newer is better.