My 2 cents in this: I have the HD650s and have used them with the Aune T1 for a while with various tubes. I thought it did fine, but I was on the verge of selling the HD650s due to an overall lack of excitement. Due to circumstances and other cans requiring this, an upgrade to a bigger budget amp (Vioelectric V200) got me unexpected and AMAZING results with the same good old HD650 cans. I can't state this enough, and as a lot of people have been saying around here the HD650s have impressive scaling potential as you get better equipment.
My Aune T1 is now playing the DAC role, until better prospects.
Overall it puts a very worthy effort and I still have a lot of sympathy for the Aune T1, but there is simply no contest once you move up the budget chain.