I cannot imagine a mainstream amplifier, or receiver manufacture allowing their product to have a "sound"; because if it's not neutral (i.e. no "sound") the manufacture will have limited their market share, because some speakers will interact poorly with whatever is giving the amp its "sound".
And as for the DAC's, if a manufacture knows how to put excellent DAC's in its flagship receiver, why would they suddenly fall into incompetence when putting them into their less costly receivers?
Now, please don't get me wrong, I do not think that every amplifier and DAC in the world sounds identical, but I do think that if the designer wants to, it is well within his or her power to make a sonically neutral device.