Speaker placement and dB differences

Last_lemming, you might try switching your speakers, left speaker to where the right one is, and vice-versa.  Assuming there are no issues upstream of the speakers (like a weak tube in one channel), this will help narrow down what is a speaker issue and what is a room issue. 

Duke

Absolutely yes. Even 1”

sorry to respond late to some of the comments.
thanks for all of them btw.

The speaker are now within a +/-1/4" from front and side walls from one another and they are toed in a bit so that their axis crosses behind my head a foot or two.

I have sound treatments on all walls and even the ceiling.  Large wall of diffusers/absorbers  behind my head and on side walls for reflections.  I have diffusers on front wall between speakers and on ceiling where main reflections would come from as well.  I also have a few large GIK wall panel absorbers as on three walls.  The floor is a large plush rug.

As for amplification, I had a Parasound A21 driving them when I had the speakers in a larger room, plenty of power, but the room had a bass suck out right where I sat that I couldn't do anything about.  I had to use a REL sub so compensate, and it work a bit, but the sound was still anemic in the mid bass and mid base region.  Now I use an ARC CL 60 tube amp and it sounds clean and full sounding with PLENTY of bass and power in the smaller room.  I feel zero need for a sub.  Based on my Omni mic im getting very good bass down to 32Hz.

I do realize the Thiels require time alignment and a min. 8' from listener position to integrate and I have just over 8' now.

Just as a point of reference when i set speakers up I try all types of placement and then once I'm satisfied about a general location I tweak further until the last inch or so and then fine tune to within a quarter inch.

It has been my experience with these speakers that they tend to sound best further apart than most with only little toe in.

As for the suggestion for time gated cures, I have no idea how I would generate such a signal.  I have an audio analysis app on my I pad and the calibrated mic is attached to to receive sound from the source - in this case a test CD from my HSU sub I once used, but nothing with a time gate on it.  Not even sure what a time gate is really, though I have a thought based on the name.

Time gating is a technique for measuring the speaker's output without including any room reflections.  A specialized measurement system is required. 

The microphone is switched on for just long enough to capture the direct sound from the speaker and then switched off before the first reflection arrives. So all room reflections are excluded from the data.  But the ability to collect good data at low frequencies is limited by the shortest reflection path length in the room (typically the floor bounce), because the microphone is off before it can adequately capture longer wavelengths.  

Time gating is one of the techniques John Atkinson of Stereophile uses when generating "quasi-anechoic" frequency response measurements.  He uses a different technique called "close micing" at low frequencies, which is where the microphone is placed very close to the woofer(s) and then very close to the port(s) and those curves are combined with appropriate weighting.  The result is then spliced with the time-gated curve. 

Duke