between hd600/650...hd600 is my center reference. (open)
closed cans...maybe the akg k271mk2, sounds neutral to me.
my dacportLX is pretty neutral, its a dac, but it powers the hd600 easily.
i wont go for the novo, it sounded euphonic, slightly warm, v airy, very pleasant.
i would go for a BCL if i want a neutral amp...the price....errrrr.
just remarks off my head.