I think the Metrum Hex is a tiny bit inferior to the AMR. Both fall into the analogue sounding cathegory, but the Hex is very slightly more forward and treble oriented. The Hex handles rock really well, anyway. I felt the AMR + JCAT combo was just a slight step closer in the Hex 'glamourous' tone, with some more forwardness compared to other cables (Acoustic revive, Gemini), and an overall more cohesive than the Hex.
Anyway, the two DAC's should be heard, few words are not enough.
I think, given the price difference is not small, the AMR would be the best deal if actually enjoying the preamplifier, otherwise the Hex would be better value for the money, if comparing the two dac's alone at retail prices.
The one who bought Greed's unit on the sale forums surely had a great deal.