Component Stacking Question

tough to get a better amp for the money and even better when parts are upgraded. Great little sleeper amps.
And yes, don’t stack them. Best to get a cheap shelf set. stable, cheap, etc.

Preamp might be decent too, have never seen a image of the guts of them. One model of preamp, from that series and company (inkel).. was good enough to the the base unit for the Adcom Gfp-1. Also sold under the sears brand, LXI.

these are both Korean inkel products. styled differently, in minor ways... and the amp is slightly modified.
http://audiopub.co.kr/wp-content/uploads/2018/01/T_adcom-gfp1.jpg

Temp is OK.

Weight, maybe. Is the preamp strong enough for the weight?

Noise - Power transformers can radiate a lot of EMF noise, which can be picked up by other equipment too close to it. You'll hear it as hum.

Stacking the amp on top is the only way if you must stack. Better off putting each component on a separate shelf, with as much room in between as possible to reduce effects of EMI and restricting airflow. Typically, the power amp needs the most breathing space, followed by the preamp and then tertiary components. Remember, heat is the enemy of electronics. 

these two specific pieces:

I would put a 1" spacer in between them so the pre-amp rear vent could do it's job, then stack away.