Recently auditioned a Mcintosh D150 digital preamp/DAC for use with a headphone setup and second audio system. Wasn't sure what to expect, but was very plesantly suprised at just how good it sounds. The headphone setup is a KGSSHV amp feeding a set of Stax SR007 phones.
One of the nice things about the D150 is that it has both fixed and variable outputs, with both XLR and RCA for each. I had occasional issues forgetting the volume setting with the Benchmark when switching from headphone use to speaker use. No such issues with the D150.
What really surpised me is just how good the D150 sounds. The D150 seems to be a better match for the KGSSHV than even the Benchmark DAC2, which I did not think would happen. The midrange espcially sounds a bit more lifelike, the bass has a bit more heft, but the treble is really where I hear the difference. Very silky smooth and detailed.
Needless to say, I was impressed enough to sell the Benchmark. While I still feel the Benchmark is among the best, the D150 just seems to be a better match with the gear I'm using.