Best Class A Amp under $2,000 used?

you wont get 250w classA anywhere. push a bit your budget if possible and get the Benchmark AHB2.  It plays well above its price and is a near perfect audio tool. You will have everything you will need amp wise for the next 15 years.

Average listening uses only a few watts.   I recommend a single end triode (SET) amp using 211 or 845 output tubes for 12 to 15 watts of pure class A power.        By the way, you did not list your speakers. Amplifier/speaker matching is important! Same for your signal source: analog or digital? 

Sorry, I missed seeing the first part of your post! Dali's/Wadia is a good speaker/source combination! I still recommend a SET tube amp (even one using 300B tubes). Very smooth and yet detailed enough to hear all the nuances in your favorite recordings!

I had a Forte 4A class A amp. Forte was built by Threshold. 50 wpc into 8 ohms and 100wpc into 4 ohms. All in Class A. They could handle Thiel 2.3's which I had at the time. When on the market they get scooped up quickly.

Sony TA-A1es integrated.