At home I've got my combo sitting on top of an unused 4x12 cabinet so it blasts directly in my ears
If I put it on the floor using the exact same settings it's like someone swapped out the speaker, the difference is like night and day, not just in terms of overal volume.
That's why I like the dimensions of 2x12 cabs like the Marshall 1966a and 2061x. Apart from the superior sound projection, you also get the put your amp at the same level as with a full sized 4x12 cabinet, so you've got your controls within reach/sight.
With a PPC212 I'd just use something to tilt it a bit
I find open backs are a much more omnidirectional source, I pull 'em off the wall a bit but they often benefit from the floor boundary as an early reflection point.
Mind you, by the time I'm plugged into the amp, I'm listening to the room and not the speaker. I also don't like overbearing highs, so my method might not be a match.
Fist I have both my cabs sitting on top of a custom pallet that has foam built into it and carpet on top that I pinned down with a staple gun. Super sturdy. Then I have my cabs on casters, which elevate them. So my actual cabs are off the floor over a foot and a half I believe. I've been known to sit on the pallet with my back to the cabs as well. So I'm going directly into the ears (probably destroying them as well), but feeling the vibrations on my back is inspiring in a way.
I hate playing directly off the floor as you're right. You're wasting frequency ranges on your knees vs ears. Now you could tilt your cabs, that would solve the problem as well. They even make some combos like that. Tilted so the air is pushing upwards and thus so is the sounds/freq.
My rig looks silly as hell, with a single milk crate on bottom, amp on the milk crate, and two cabs stacked on the amp. It looks precarious and probably could get knocked over without much of a push. But it sounds better to me with my speakers off the floor. Prople should just do whatever works for them though. Sounding good to yourself is a huge benefit, for me it's foundational to making music, if I don't like the way I sound I really end up hating making music. Transmitting that good sound to other people is another trick, a trickier trick. I usually just leave that to the soundman, once in a rare while I might ask a trusted friend how the room sounds but most of my friends are worthless at this, so I don't bother.
I play sitting on the floor. I use cut up left overs of a cheap yoga mat that I destroyed under the amp to isolate it a bit from the floor and keeping the neighbors away from my doorbell. Works a charm.
Small combo: On the kitchen table, stand a few feet back. Make sure there's nothing that can shake or rattle on the table.
Bass: On the floor, and stand at least ten feet from it.
Tom Dalton wrote:"I want to be as big as I can if it's going to stop a bullet."
