Before you spend a lot on an expensive amp, swap the HD600s for 650s. It is a night & day difference, a much more open sound with far better separation of musical components. The 650s are about $350 (street price from a Google search), an incredible bargain. Then,
get a good headphone cable like the Zu Mobius.
I use an old Headroom Max with fine results. It competes favorably with my tubed Stax Omegas -- not quite the same midrange purity, but a fine combination of relaxed, refined sound with just the right amount of detail, very comfortable and great for long-term listening with no fatigue or bordeom.
Interconnects make a big difference, with Kubala-Sosna Emotions the best I found for the Max but Cardas Golden Refs performing well for the price.
There is a new Max out for $3K I have not heard (with good reviews on Head-fi), but I think Headroom has some of the old ones left.
get a good headphone cable like the Zu Mobius.
I use an old Headroom Max with fine results. It competes favorably with my tubed Stax Omegas -- not quite the same midrange purity, but a fine combination of relaxed, refined sound with just the right amount of detail, very comfortable and great for long-term listening with no fatigue or bordeom.
Interconnects make a big difference, with Kubala-Sosna Emotions the best I found for the Max but Cardas Golden Refs performing well for the price.
There is a new Max out for $3K I have not heard (with good reviews on Head-fi), but I think Headroom has some of the old ones left.