I hate to ask a dumb question, but I know nothing about headphones that require amplifiers. Are the headphone jacks on my existing speaker amplifiers suitable for a pair of 600ohm headphones? I would certainly think the amps have enough power, but I don't know if the design puts any of that power to the headphone jack. Perhaps the amplification is for the speakers only and the headphones are just a pass-through of the line in.
If it makes a difference, the amps are a Yamaha RX-V673 and an Audioengine N22.
If it makes a difference, the amps are a Yamaha RX-V673 and an Audioengine N22.