I'm using one paired with the BMC S1 amp, so my volume control is via the DIGM input ... not the built in attenuator. I think it's an exceptional piece, especially if using a BMC amp and the DIGM.
However we did do a brief comparison to an Aesthetix Calypso Sig pre and the BMC pre section both fed by a Simaudio Eclipse cd player. In that setup the BMC was clearly more resolving, had similar soundstage width but much greater depth. The BMC also put images more clearly defined in space, the Aesthetix sounded a bit smeared together in comparison. The Aesthetix had more bass, but not better bass. Bass from the BMC was more fleshed out and greater tone.
I am a BMC dealer just so you know. But they are the only product line I'm a dealer for. Since I spend all my time building speakers, I'm only interested in carrying truly exceptional products that are worth my time doing so.