Look into the new async version of USB DACs as this seems to be the most noteworthy improvement made in the past couple years. Wavelength offers the async version in the Brick & Cosecant. Not sure if there's an async option for the Crimson.
I used to own a non-async Cosecant and changed to a non-async Ultra Fi Times iRoc in 2007 which I'm very happy with. In my system it was a noticeable improvment as the dynamics and bass were improved over the Cosecant. The dynamics and bass improvement could be the result of the current-to-voltage output design as the iRoc has very low impedance compared to the Cosecant. I'm not an EE, all I can tell you is what I hear.
Ultra Fi Times is about to release the async USB DAC and the preliminary reports from people that have heard it are quite impressive. You may want to wait until the dust settles a bit, but it sounds like you want to go the async USB route.
I used to own a non-async Cosecant and changed to a non-async Ultra Fi Times iRoc in 2007 which I'm very happy with. In my system it was a noticeable improvment as the dynamics and bass were improved over the Cosecant. The dynamics and bass improvement could be the result of the current-to-voltage output design as the iRoc has very low impedance compared to the Cosecant. I'm not an EE, all I can tell you is what I hear.
Ultra Fi Times is about to release the async USB DAC and the preliminary reports from people that have heard it are quite impressive. You may want to wait until the dust settles a bit, but it sounds like you want to go the async USB route.