I too was in the business and a dealer I was with brought the MB Quart line on board and mentioned, they were relatively expensive. The relationship with their home audio products did not last more than about two years or so because they were poor sellers. Nothing to do with quality of product but the sales staff, myself included, found it difficult to get "excited" about them. The clientele was mostly oriented towards rock/pop music so based on character of sound produced, other speaker lines had greater acceptance. It may be different now but back then my general assessment of the MB Quart line was that they were "thin" sounding. I was not involved in the sale of car stereo which was a different department, but I recall MB Quart doing better there. Not a top seller by any means but lasted longer than in home audio.
Based on size vs price and continent of origin, KEF, B&W and Celestion sold in greater numbers. Ironically an East German speaker line, RFT, sold quite well too and it could not have been based on looks. One in particular BR26 (aka by that retailer as Classic's) was probably the best selling model.