Speaker Height Problem

I recently dipped my toes into building a dedicated 2 channel system, with pertinent components for this discussion being an Anthem STR integrated amp, and Paradigm Persona 3F speakers. In general, I am very pleased with the upgrades from my home theater listening.

However, while not thirsty for huge low end performance, some music has sounded as though it is missing some mid and low end, to the point that I am looking at sub options.  And I have run ARC each time I add a component and/new cables.

My listening room is approximately 13’ wide x 20’ deep x 10’ high.  Due to original configuration of the room as a theater, my primary listening spot is centered 10’ from speakers and elevated 6” on first viewing platform (ie speakers are sitting 6” lower)

My laser level has my ear height at 8” above the top front edge of the speakers (11” above center of top tweeter). When I slouch down 11”  they sound like different speakers!  All of a sudden, not only am I getting mids and lows I wasn’t hearing, but the sound stage sounds deeper.

What is the ideal level height of the speaker top tweeter with relation to my ears? The 3F’s have 4-driver, 3 way floorstanding bass reflex.  

What are my placement options?  
I’ve thought maybe a raised box (which would need to be very sturdy…any suggestions?), or even a wedge that would tip the speakers upward enough to aim at ear level.

Any advice is greatly appreciated…thanks!