Try the Optimal Transient XD and DD. LCD-2F would elicit more mid-bass in XD, more sub-bass in DD (vs plain Optimal Transient). And it has the Mininum Phase filter too. It's like rolling tubes or having as many DAC units.
There are some expert reviewers here saying Sabre DAC chips sucks because they're digitally glary...obviously they haven't heard the Audiolab.
And great synergy with my D7000's.
But it shines with just about every HP I own...
My Audiolab 8200CD doesn't have a HP out, but using the O2 I don't feel the need at all for an "expensive" or "bigger" amp. Just curious, how does the M-DAC HP out/amp fair with the O2, if you (or anybody) got the chance to hear them.