Don
Its had me interested and from the tons of info in the Keyboard Corner thread it seems to work best at least 6 feet away and tilted back against a wall or better a corner. The bass will be reinforced and the side speaker will reflect better. Some guys are putting the amp on stand either vertically or horizontally. Either way the reviews are fantastic even for guys in rock bands. For an arranger I agree you would need a sub.
Good luck with it and keep us updated.
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Bill in SC --- Roland BK9 (2) Roland BK7M, Roland PK5 Pedals, Roland FP90, Roland CM30 (2), JBL Eon Ones (2) JBL 610 Monitor, Behringer Sub, EV mics, Apple iPad (2) Behringer DJ mixer