In search of low powered tube amp that isn’t overly hot

You may want to add a very small fan to keep your amp cool. Amazon sells them from very small to larger units. I'm using a Mini, Compact 40mm x 20mm USB Fan which plugs into a small USB phone charger to keep my set top box cool.

Amazon.com: SCCCF Mini, Compact 40mm x 20mm USB Fan, for VR Gear, Aquarium, Roku, Router, Raspberry Pi, Cosplay, Helmet Cooling Ventilation : Electronics

What is your speaker at office?  Is it high efficiency (> 92dB)?  If so, Atma-Sphere Gem might be a candidate.  It uses small tubes such as (EL95 / 12AT7) and generate a lot less heat compared to big push pull tube amp. 5W sounds w/ sense of realism, not cheap but within your budget.

If you are willing to consider an amp like Sugden, you might as well consider a Pass Aleph 3 or 5. Sugden amps tend to get really hot. I know Musical Fidelity came out with a similar type of amp as the Pass and Sugden. I don't remember the model, but I know its not too expensive and I've heard a lot of good things about it.

Take a look at Dennis Had’s Inspire amps. low power, yes…6 to 12 watts depending on the model, great sounding, hell yes! Hot, not so much. I have a KT-88 that outputs 8-10 watts depending on tube compliment and it sounds better, more layered, textured soundstage and sweet mid bass, mid range and extended highs with Klipsch Heresy II’s @90+ db sensitivity.  Runs cooler than my Cary 300SEI, also designed by Dennis Had, and sounds amazing. He builds them by hand in a small workshop in Cary, NC. KT-88s, 300b’s, 45’s and other output tubes. 

so much good advice.  thank you all.  (love the picture with reel to reel in the office!)

On Dennis Had, where do I find those amps?  I not finding a webpage for him.  Is there a distributor?  Thanks!