Sendy Aiva isn't hard to drive (I guess), and Sundara (next on the shopping list) either.
Currently, Aiva is fine with Fiio BTR5. D40 can also be "upgraded" with a dedicated headphone amp if I really need it (or rather want it).
D40 is probably be overkill for both headphones, but yeah it's an...
I think I'll go with Loxjie D40, although still liked better DX7 pro design and output options. That's a shame that Topping haven't got any direct successor for this device.
What's the recommended all-on-one ballanced headphone amp+dac (with Bluetooth)?
I looked at Topping DX7 PRO, but it seemed to be discontinued. What would be an alternative?