So far so good. My first foray into Class A amplification was the Aune S17 Pro. I chose it because of the price. Was forced to return it. Was running MUCH too hot using ZMF headphones and the 4.4mm connection. Internal temperature was 75C. The case was over 45C.
Found a good deal from headphones.com on a non-returnable Soloist 3XP. It arrived in excellent condition. The packaging is crazy good. Sounds great so far.