Re: tall stand for sierra lx?
These go to 45" and are rated up to 130lbs, so Sierras definitely won't be too heavy:
https://www.monoprice.com/product?p_id=625870
They also make ones that clamp onto the desk:
https://www.monoprice.com/product?p_id=600024
Never used them myself but monoprice stuff is usually pretty solid, if perhaps not the most aesthetic.
Luna Duo V2 LR, Titan Horizon V2, and Rythmik L22 & L12 in HT1; Sierra-LXs in study; S-2EXs and Duo V2 C in bedroom; S-1 NrTs in dining room; S-1s at work; HTM-200s in kitchen. Brother owns CMT-340s and dad has a pair of CBM-170s.