The three things I care most about in an amp are (1) non-analytical sounding [it hurts my ears] (2) mid-range weight / vocal realism-emotions [non-hifi people notice this most on a quality system, in my experience] (3) sufficient bass to create the soundstage.
My experience in lower priced class D amps is they typically fail in (1) and (2). Are the OA amps, near tube amp (EL34, 300B) quality in (1) and (2)?