dual ba are not hugely different and are not best at bass , most of them do flat frequency , what they tend to do is speed and texture , my ue 600 and 700 sound nearly same , but the ue 700 are faster , better highs and nice body . b2 is not different at all . for starter stick to single ba , better single ba are nearly on the mark with the dual BAs like sba-3 . your choice , its all on you and the main question is what you want ? just wanna say its your first BA , dont rush in , but the b2 are really awesome , a tad better then my ue 700 , auditioned extensively , cuz i was getting mad for them , but settled for xba-3 cuz they sounded better to me with a bit more bass , b2 sounded nearly exactly same to my ue 700 . i would say get the am-90 , if you need more get the b2 .