Stacking pass labs power units??

Two Class A units produce a lot of heat.

Very bad idea.

@chorus the units he is describing are a phono pre and preamp, neither really produces much heat overall. 
 

To the OP, it should be ok to stack the power supplies. But keep them away from the other units. I would keep the phono pre as far from everything as possible. Having said that, stacking the two pre’s won’t hurt anything, but you might find a bit of noise possibly. 

Thanks for the replies and instruction. I'll do as builder3 suggested, and just call Pass on Monday to see what they say.  Thanks again, everyone. 

Why not just try it see for yourself?

True.  I will try it, but wanted other thoughts and will see what pass says.