I did not have the chance to hear the DQ-20 or DQ-30, but lived with the DQ-10 for several years. Don't want to get off track of the questions you have asked, but you might want to go to the Acarian Alon site. This is the company that has gone the route of where Dahlquist might have gone. To many, the line of Alon speakers over the last 10+ years are the right choice for fans of early Dahlquists. If you go to their site, click on the reviews..and you will read about the family ties between the early Dahlquists and Alon. For what it's worth, some of their speakers have been TAS Golden Ear Award winners.
Best of luck.
Best of luck.