The 650s sounded amazing with the HiFiman EF5. Totally awesome sound out of the box.
My EF5 was defective, so I returned it, and got the Lyr instead, because I see it as an amp that can grow with me as I keep delving deeper into the hifi mire. Silly me, I should have read these forums in more detail before ordering the Lyr with the JJs tubes. Schiit is sending me out another set to try.