Dear @chungjh : I already talked about why we need to listen our room/system seated at near field position. Please re-read my post.
In any room/system the seat position of the owner is critical for several reasons that includes each one of us hearing lossed, SPLs each one of us prefers and so on.
Good that you improve changing your seat position and then you need to follow about from where you are testings with small/tiny seat position changes looking to find out the " rigt " one position and remember that behind that seat position should be romm/treatment too.
In the other side, try that your audio retailer browse to you at your place a Pass preamp or something similar to the Pass one.
No, it's a very bad move to change the 545 speakers for other speakers when the trouble is not there but is up to you.
Btw, o you already tested 3-4 different hedashells with your cartridge and tested with different headshell wires than the stock one?. This was my advise to you in your tread in 2021. Again, is up to you because I really don't care if you did it or not because at the end is you who must live with that audio system.
R.