I have not heard the Jot 2 so I cannot be of much assistance there.
But, honestly, I am thankful that my HE6seV2 ownership pushed me to pick the FA10. I essentially bought the amp for these headphones alone. Now that I have been listening to my other phones on the FA10 I am so happy I purchased it. The high wattage and class A current output seems to make everything in the collection sound better. The Clears sound great; the HD650 has never sounded better to me; I’ve got some Argons that I haven’t listened to in over year that are just killer through the FA10.
Having experienced the FA10 now with my other phones, even if I did not own the HE6’s, I would buy this amp.