Didn't keep the Rock for very long to make a comparison.
One thing I am certain of, however, is the Rock can accommodate a wider range of ear/headphones because its gain is not as high (even on High Gain), and can be adjusted to Low Gain via jumpers. The Vali is only usable with less sensitive headphones.
I don't know about an Asgard 2, but I have a Vali and owned a Rock for a year or so. The Rock definitely runs much cooler than the Vali; it only gets mildly warm to the touch (this coming from a guy who can't cook to save his life for fear of fire, so there you go).