Again - the Heresys are extremely efficient which gives you a great opportunity to play around with some low-watt tube amps including but not limited to SETs, which will give a far more detailed, engaging and magical sound than any hulking solid-state McIntosh will give you - especially if you're willing to shell out what an MA6300 would cost.
Mating a SS Mac amp with Heresys is like mating King Kong with Fay Wray.
Look into Almarro, Decware, Miniwatt, Bottlehead, or the vintage Scott that was mentioned, a nice Eico HF-81, etc.