Bokat57- I received my Rachael at the end of last October. Fantastic amp, even better with my new (160+ hours so far) Omega 7XRS speakers that are 95 dB and 8 ohms. A fantastic match, plenty of power and the amp and ZP3 phono are just making magic on a daily basis. HEAT? I have all my gear in a coat closet that is in the living room and even with the door closed and all the gear on, it only raises the ambient temp of the closet about 10 degrees. I was worried so I purchased the same calibrated digital therm that I use in our QC room at work and it is a non issue, in my room. I would not really worry about it. Enjoy and post your findings. What speakers are you going to be driving with the amp? Let me know if you have any other questions, this forum is amazing. Happy listening, Chris.

Bob- With my cd (have not replaced the DAC yet) is have no hiss or noise through the Rachael/Omega combo at my listening area, volume wide open. That is WAY louder than I could ever listen to it. With the phono I still have a very small amount of what I call ''motorboating" which I determined was the ZP3 being near the Rachael, but that is also with the volume set WAY higher than I could ever listen to the phono. At normal volumes, pretty quiet. Running stock tubes now since I just got proper speakers for this amp. I will play with tubes next fall/winter. Heat, not a problem at all. Love the Decware/Omega set up. Listening to Rodrigo y Gab live in Tokyo last night and the presentation was just magical. Happy listening, Chris.

Bob, It depend where do you live.
A tube amp in Canada is one thing, the same amp in Mexico is not suited to use in summer.
It may need air cond in the summer if one live in a hot area.

As I consider exploring a low power tube amp, high efficiency speaker setup, this question has also been on my mind.  The space on my rack is open front and back and 20 inches wide.  The height is 10 inches from bottom to top.  

Will this height be a problem?  In the worst case, I could drill holes in the top of the rack to let heat escape but would prefer not to do that.  The Mini-tori may also be a better fit for that rack space.  Any insight or comments on this are  appreciated.  

Height is a factor for many of the hi-fi racks that are happy with ss gear, cd players etc but not for big tube amps. I had to lift off a shelf, put in the ZP3 and replace the shelf. The limited headroom meant that I taped tin foil to the underside of the shelf above it to help dissipate the heat from the amp and stop the shelf getting hot. They were early days with Decware and I`ve since move the amps to one platform where they can all get warm together with unlimited space above.
Regarding the room getting uncomfortable with the heat from the tubes. I`ve got 4 amps running in a 12x9ft room. Winter time I still need the radiator on when it`s cold outside ( UK cold, not US v/cold ).
Springtime when it`s still cool I`m not thinking more heat which I may for the rest of the house. Summer when it`s hot outside the room feels like it`s gone up a few degrees, but as I listen in the evening it`s all good. A window and a door open trying to find a little breeze is a perennial pastime.  
With one SE34 running I doubt you`ll notice any change.

If you have real concerns about the temp of your gear, I used to use and sell products from ATM (Active Thermal Management) when I was in the custom install business. Might be too much $$$ but you can get ideas about what you can do with a little whisper fan and some imagination. They are really good products, but the ideas are good also. Happy listening, Chris.