Cabinet clearance for Audio Acoustics LS16 tube pre-amp?


I am in the process of designing a built in cabinet for my stereo system. The owner's manual for the Proceed HPA2 amp is very clear about clearances for air flow. And even in the summer it almost never feels very hot as it has enormous aluminum heat sinks with completely open airflow from top to bottom.

The owner's manual for the LS-16 does not give any specifics. It says things like "adequate airflow" and that with a closed back cabinet, which mine will be, an exhaust fan is "desirable". That's about all they say. And it runs noticeably hotter than the amp. The top is never too hot to touch by any means but it is warm to the touch. Currently it sits on top of basic component stand and is up on some raised blocks so it gets all the airflow it could possibly need.

I could put it on top of the built-in shelves but I'd prefer not to. I'd also prefer not to have an exhaust fan humming along all the time. But, I don't want to shorten tube life or hurt the unit either.

Any recommendations? Precautions? Prior experience with your set-ups with tube pre-amps? 

Thanks,

George
n80
Thanks. My shelves will be open front and there will be vent holes under the amp and pre-amp as well.

I think the pre gets great air flow sitting on top the way it is now but I'm also sure it gets a fair share of dust (and dog hair) too.
The key to these devices is often in the power specs.

45 Watts. A lot more than a solid state pre, but not unreasonably.

I'd say 4" ideal, 2" minimum, since it has to have enough air to go in and out the same way.
The amp manual recommends 2'-3" of clearance. I'll allow for more for both components. And even though these shelves will be closed in the back and on the ends there will be lots of space around each component. The LS-16 pre amp does have grill on top and bottom so it can draw air up and through. As mentioned, the shelf below both of them will have vent holes.
Cabinet is probably not the best term for what I'm building. It is shelves. Open in the front. No doors. There will be 3-4" clearance above the unit. Vent holes below it and a good 8 inches of clear space on either side of it.