I've owned 3 pairs of these, the NS1000’s can sound a bit in your face, but still need an amp with great bass control or they can sound a bit fat down low.
A good smooth solid state, with high class A bias would be good to keep the in your face sound under control. Maybe a good (reconditioned) second hand Krell KSA-50 or KSA100 fan cooled very high class A bias. And yes the Halo A21 or A23 which are also high bias.
Cheers George