I owned both the 4490 and multibit versions of the Bifrost doing direct comparisons with my Valhalla 2 and HD650 combo.
A beautiful pairing with the hd650.
I quite agree. I went from Bifrost Uber-Valhalla-HD650 to Bifrost Multibit-Valhalla-HD650 and I really like the multibit combo. Very natural, musical and non-fatiguing.