low frequencies

I have a pair of Thiel 2.4 in my second system. They were in my main system for a few years. I have owned them for a very long time and have had them in 4 rooms with at two different houses. The Thiels have great low bass extension and texture. Mean really good. But it is tuned flat so not boomy at all. Typical HI-Fi turned bass.  
 

this is 100% a room issue. Try pushing the speakers back so the driver face is 24” off the front wall. The sound stage will still be fine and the bass will be impressive. At that point if you can move your chair around until the bass sound good, sit there. 

the key is: those speakers, in that space, at that location

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I suggest: Get thee a simple Sound Pressure Meter, tripod, set at ear height at listening position

https://www.amazon.com/BAFX-Products-Pressure-30-130dBA-Warranty/dp/B00ECCZWWI/ref=sr_1_4?crid=1BZ6BV6ZMIG39&keywords=sound+pressure+meter&qid=1686325343&sprefix=sound+pressure+meter%2Caps%2C73&sr=8-4

next a test cd with individual tones. Note: I scanned several Stereophile Test CD’s, others, none of them have the full range of frequencies this test disc has (29).

https://www.discogs.com/release/7290000-Various-Amazing-Bytes

you will know how flat of a frequency response your speakers are producing, IN That Space, AT that location.

Next, try new positioning and different toe-in, measure the differences.

Amazing Bytes is hard to find, and expensive, I can find a used copy if interested.

TY for the suggestions DILL, The distance is 10ft ear-tweeter distance. Funnily enough I have moved the couch back another 2 feet and bass is sounding much more full. Polarity is all good😎

AM Acoustics room mode simulator is a great place to start. Look at the lowest modes and try to keep both your speakers and listening area out of them.

After that, it's good to measure to see exactly what your problem is. 

James633 thanks for sharing those thoughts. You have a lot of experience which is always nice to hear about. I was able to get much better sounding bass from a seated listening position by putting the couch further away from the speakers. Now at 13 ft from the tweeters and 3 ft 6 in  wall behind me. I think it was a bass null where I was before.