Speaker stand height

Try to use stands that get the tweeters at about the same height as your ears. High-frequency sound is directional, and you'll notice better sound if you do this. If you need a custom stand height, Sound Anchor makes excellent ones.

Speakers' beam isnt the same as speaker hight. I too set relitively low and made some 18" stands with about twelve degrees of tilt back. The low height has the driver closer to the floor boundry thus richer tone. I avoid on beam listening by having the driver go over my head instead of toe in behind me as that would create more side wall reflection. This enables a stage height just above my head and creates a 'you are there' instead of a 'they are here'

"and may powdered sugar fall upon your ears tonight"

The heigth depends on the speakers. Some speakers sound better with the area between the tweeter/woofer amed at your ear level. You can also tilt the speakers forward to achieve this. A good way to get equal angles on both speakers is to use a laser pointer.

PSB Speakers with the tweeter under the midrange/woofer are designed in combination with their crossovers to beam the sound slightly upwards, so there is not a big difference in sound when you are standing or sitting. That is just one of Paul Barton's design quirks. So, maybe try listening to them upside down to beam the sound a little lower.

Here's another idea which is unconventional but you might love the sound of it; turn them on their side, like a center speaker. You might be shocked at how the sound changes when they are turned, let's say, on their side with tweeters inward. That change in elevation of the tweeter of several inches may do the trick, and the placement of the bass outward and tweeters inward is more like a panel speaker. Give it a shot and see what you think. Costs nothing and you may like the sound a lot. Also try them with the tweeters to the outside and you will likely sense the soundstage has widened a bit. Of course, then you can also work with their placement, distance from each other as well.

You can also take a couple rubber washers or similar - or better yet some stick on rubber feet or blue tak, and set the back of the speaker up ever so slightly, moving the directionality of the speaker downward. Between these two ideas you likely could find a solution without having to buy new stands.

Manitunc's suggestion of turning them upside down is also a good one. Once or twice I have taken modular speakers costing tens of thousands and turned the upper module containing an inverted driver array upside down to see what the speaker sounds like when the drivers are lined up more traditionally (smallest to largest from the top), a very enlightening experiment.

There's plenty of things you can try. Sometimes it's fun, even when you have your optimal positioning, to turn them on their side just for kicks/variety. :)