ubk,
my thoughts are not based on 100% speculation as I owned a Rosetta800 for a long time. It´s color is not as evident as the pretty huge difference between the burl and the apogee files here. I am pretty sure if I ran a signal through the rosetta and post original and the extra DAAD version, most would not be able to tell them apart. the burl vs the apogee however is easy to point out. hence my assumption that the burl adds more of it´s own sound to the source. makes sense to you?
in addition I find it my speculations no more absurd than some of yours, like that all the components are responsible for the burls evident coloration. how would you know? did you take it apart, exchange all the parts and listen to the results to find out? I doubt it. maybe there are 2 or three key components (among those the transformer) that are responsible for "that" sound....there is a good chance that those components could be isolated without the digital part of the unit to build a pass-through coloration unit at a lower price.
and about the "biased" part, yeah, maybe I am biased, but I think someone who got paid by the manufacturer is not in the best position to call others biased
best,
pat