@budburma Yes the Line Magnetic is borderline for power in my room which has only 2/3rds the volume of yours. This using a DAC having 2V output.
I am with you on the use of a tube preamp with a SS amp. I run an Aric Audio pre into my XA25. Also have an Aric Audio Transcend tube amp which I rotate in. Both provide more 'juice' than the LM.
ALso like you I am not sure that my Sterlings are fully broken in.
I will say that I like the LM integrated. With the right speaker/room it plays well. My issue with it is that it has a sensitivity of 200mV. Way too high in my book. I am thinking too much gain in the preamp stage, not sure about this however.