I suggest you upgrade your DAC before you sacrifice the Thiels. The 7.2 are good speakers and I have never heard them sound too bright. The Lamm is an excellent amp (my subjective opinion) and I’ve never heard it sound harsh / bright either...
Why not audition a few DACs (for example, Ideon Audio are very dynamic w/out being strident, Benchmark is good too, as are many others).
The Lamm pre is excellent, should you wish to add a pre
Regards