[Arran]

 Rola was just a speaker manufacturer as far as I know, much like Utah or Quam Nickels, I've seen their speakers used in a bunch of different makes and models not just Detrola. Besides that Detrola was really not a large enough manufacturer to have bought out a speaker manufacturer, or made their own. Or were you thinking that the 'rola portion of Det-rola had something to do with the speaker company? I think that ending a radio or phonograph manufacturer's name in 'olla was just something that began in the early days of gramophones and carried on longer then it needed to, like Victrola, Graphonola, Phonola, Radiola, Audiola, since Detrola sets were made in Detroit they just dropped the "it" and added "la".
 Yes the styling of that set is very similar to that of a Philco 60MB or 66MB, but was likely inspired by the Philco models rather then the other way around. Philco used their own stylists that they had in house but also hired outside stylists like Norman Bel Geddes to design cabinets, Detrola may have done the latter but more then likely they just hired an outside cabinet/furniture company to design and produce the cabinets for them.
 Dennis Smith (Mr Detrola) may know for sure what they did over at Detrola, he apparently had an Aunt that worked for the company hence his person interest in the history and products of the firm, but most of the small and mid sized radio manufacturers did not have their own cabinet shops and contracted out. They would go to a cabinet company and if they did not have something that was already available off the shelf the cabinet company would submit a few designs for the radio manufacturer's approval, which they would then build.
Regards
Arran