We all seen discussions on speaker placement. Most of the discussion is centered around tilt, room placement, and symmetrical placement in the room. Well not so much on the symmetries.

In my room symmetrical placement has always been sought or at least somewhat. The speakers were always placed the same distance from the sides and back of the walls. Toe in was done with a laser so the center of each single driver is just past the side of ears. The speakers are carefully placed with a level to be plumb. The speakers are isolated from the common concrete floor. This has always produced a great sound image in the room. However the system has always suffered from balance. I tried everything to eliminate this issue without success and concluded it was a inherent hearing problem until now!

I was doing some trouble shooting that required the speakers to be moved. When resetting the speakers it was noted that one is about an inch higher than the other using the laser on the tops and after leveling! Hmmmm! Concrete floor is not level which is kind of normal. This might be the balance issue root problem.

To fix this will need a good bit of time. It will have to wait for another day. It was also noticed afterwards when listing to music in the sweet spot if my head is tilted a bit higher on the higher speaker side the balance issue seems to dissappear!

Food for thought.

John

Aside from my primary speakers, I have the Lii "origin" cabinets and have used both the C-10 and S-10 drivers; I found they are very directional with a narrow dispersion in the upper end (my hearing stops at a bit less than 14 kHz). I'm not clear on what cabinets you have, but have you tried a slight down tilt on the high one (or up tilt on the low), or increasing gain on the low/high side via the CSP? Just curious about what all you've tried, as I had a similar issue but seem to recall it was a bad input tube... just not evenly amplifying higher frequencies on both sides, or so I thought at the time.    

My ears also suffer from hearing loss. Now, anything over 10k is mute. It starts to drop over 8k fast.

I tried new tubes, amps, speakers, switched drivers between cabinets, new ICs, cables, CSP2, etc. Found that trying to do level control adjustments with the CSP2 works when adjusted but the next album/CD it changes. Sometimes it can change on the next track! It can also be the material, but it seems all is slightly to the right.

I am going to put the folded horn cabinets on the same horizontal plane and see what changes. The cabinets are on platforms now with spikes into the concrete. The spikes are not long enough to make up a 1" difference because of the carpet. Need to find heavier spikes or add a spacer board to the right platform 🤔

John