Hey Nigeljames - and thanks for the response.
I've previously owned the Lyr - an excellent amp paired with my LCD-2's. Only sold that to make way for the Mjolnir, really.
And well, I guess there is still a price difference between the M51 and the Gungnir, but couldn't that be attributed to all the (in my opinion) silly bells and whistles on the M51? I'm pretty much after good stereo sound, that's it. Not HDMI, not a preamp - nothing of that.
If you're saying that the NAD actually delivers at least "on pair" with the Gungnir I'll have to sit down and ponder. Can get rid of my DacMagic right now, but that would mean I'd need another dac - and the M51 is available now. Hrmf - hard to make a decision.