Component Stacking Question

Can I stack my Amp on top of my preamp ?
Will either component be negatively affected by doing this?
I have a Sherwood Amp 6040 with M0S FET push pull DC that runs warm.
My Pre Amp ...Sherwood 6020 
Components are not in a cabinet.
Thank you

Then how do you explain how an integrated amp works? It's all in one chassis in even closer proximity to the low level preamp section, and seemingly sounds ok....I see absolutely no issue in stacking.
Audioguy85 you don’t understand the OP’s question. The whole point is to optimize placement from cooling/airflow and interference perspectives, it’s not not about what is or isn’t possible. 
Stacking is usually done because of space considerations, at least in my case. But if I have to do it, I use a platform/bridge that I have a friend custom-make for me at little cost (usually around $50). Simple but effective. Personally, I would not stack an amp/preamp unless there was no other choice. I'm also a believer of cooling fans for amps in 'dense' installations.