I would get Isoacosutic stands for the speakers and you can experiment with the tilt and decouple from the shelves. Next I would see about back filling those shelves with acoustic treatments. if you post a pic it would help.
Front Wall with Full length Workbench Shelf
I’m slowly tweaking a 2nd system listening area in a 14’ x 24’ dry walled metal building. The only available speaker wall is the short wall and this wall has a 24” deep shelf running the entire length of that wall at a height of 38”. My bookshelf speakers sit on “diving board” type extensions which bring these Klipsch RP-600Ms out from the wall a full 3 feet and some change at the 38” height (They’re angled down ever so slightly.). Thinking about adding REL T-5x or 7x sub or subs in the near future. Do you all see the “compartment” effect produced by the continuous 38 inch high, 2 ft deep shelf potentially directly above these subwoofer(s) as an advantage, disadvantage, or non factor? If it’s bad for SQ, how would you think the best way would be of minimizing deleterious effect while keeping the continuous workbench surface intact?
Thanks in advance!