In a similar position myself looking for a tube amp around this price bracket. Recently had the opportunity to demo the HA2-SF, using my Empyreans paired with the DAC from the iFi Micro Black Label. Here are some of my rough thoughts (keep in mind that this was in a store with quite a few people, so given my HPs are open back, the circumstances were less than ideal.
A huge improvement to sound stage, with noticeably better imaging compared to the on board amp of the Micro BL. I would say that the amp sounded less coloured if that even makes sense, the Micro BL being a great portable unit just does not compare, bass was a lot more defined, and hit a lot harder, the mid-bass was more controlled and didn't bleed into the mid's not nearly as much as the BL, treble was sparkly, with great resolution but smoooooth without too much roll off or loss in resolution, I am extremely sensitive to treble but never once during the audition did I feel I needed to turn down the volume (other than when the music I was playing was getting too ridiculously loud), being new to the hobby and especially to tubes, this was not the gooey warm experience I was expecting from a tube amplifier, but overall a very enjoyable experience.
Build quality was top notch, the materials used felt great to the touch, all the switches felt sturdy and smooth.
So all in all a great unit, the only reason I held back from the purchase was because there are other options on the market that I want to try out before I buy, including the feliks euforia, the primaluna evo series integrated amps and the newly released mha200.