height to place wall mount speakers

Hi.
I'm planning to wall-mount a pair of Totem Rainmakers. (I spoke w Totem and they said mounting them is perfectly fine.) I bought a pair of wall-mounts that have side clamping brackets that fit on the underside of the speaker so no screwing or other permanent molestation of the speakers needs to happen. The mounts allow for a 7 degree tilt, though I'd prefer to have them horizontal (mainly bc I'd be nervous about them sliding out if they're tilted down, even though they'll be clamped tightly of course).

The speakers are for our living room, and I expect my listening will be split 50/50 between sitting on the sofa 10+ feet back facing them and standing moving about as we entertain guests or just walk around our apartment. Does anyone have recommendations on a good height to mount them? My instinct is to put them at about standing head level thinking the sound will be perfect for standing and will flow down nicely when sitting. If I put them lower I'm afraid it will sound weird when I'm standing. In other words - does sound tend to work better flowing down than up? Will I hear more or less bass or treble the higher up the speakers are placed?

PS. I can't really test out different heights bc once the brackets are screwed in that's it and there's no way I can think of to temporarily hold the speakers at a certain height to test.

Thanks in advance.