I don't believe the Susvara is all that tough to drive. 30 ohms and 2V of drive certainly isn't going to be available from a smartphone, but the Kaiju and SEX amp will provide that easily, and a Mainline would probably be OK too. The AB1266 would likely benefit substantially from the power available from the Kaiju, and being able to wire the Kaiju up to 16 ohms would give you some extra output level that you may want with those power hungry cans.