but i don't know!
i have the 770s and 840s. love both.
but am liking the 770s a little better recently.
problem with the beyers is which impedance. my 770s are 32 ohm and sound great out of my pioneer reciever. So maybe i go for the 990s in 32 or 250 as the pioneer might not have the voltage swing for the 600s.
plus neither the 840 or the 770 are incredibly detailed accross the spectrum so maybe i need the 940s.
hell i don't know