I've heard both, side-by-side and of course value is relative to the individual, but the II+ is better in many ways -- better soundstage, quieter, better bass dfinition, smother and just a nicer presentation -- and the Crack can certainly reveal these changes no problem.
The II is a superb dac for the money, but the II+ does take it up a few notches. Then add a decentt usb cable and something like the aqvox usb linear power supply, hide it behind everything, put a high-end cdp in front of it and nobody would be able to tell it was the little HRT making the music. Of course the real best performance comes only with a very good server to feed it. It's digital -- everything matters.
I've not heard the HRT MS Pro though so can't comment on that one.
Next I want to try their LineStreamer 24/96 ADC connected to the Eros and using PureVinyl.
-- Jim
Jim Rebman -- recovering audiophile
Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).
s.e.x. 2.1 under construction. Want list: Stereomour II
All ICs homemade (speaker and power next)