Have you ever tried running the DD12+ via high level input? I run a pair of DD10+ and thought I liked the match better when powering by speaker cable from amp terminals. I do have to keep the speaker level gain low - about 20 percent from lowest setting to get clean bass. The Velodyn coming in at 40 Hz (actually lower using am eq curve really helps flesh out my TAD's and allow the bottom end to blossom.