What's the best Line Magnetic SET amp?

Maybe a Line Magnetic Analog Sound AS-125 

I own, and like SET amps, but, I don’t think they necessarily sound better than pentode/tetrode pushpull amps.  There are many fine lower powered pushpull amps that sound very good.  To me, the best sound from SETs are achieved with the lower powered tube types, such as 45s, 2a3s and 300Bs, and some of sweet sound and liveliness at low volume is sacrificed with transmitter-tube SETs.  A builder told me that the wiring needed to provide the high voltage on the transformer primaries and other aspects of transformer design compromises the sound of high powered SET amps; this designer generally favors two tubes per channel pushpull (does not like parallel pushpull).

I would suggest looking at amps running nice sounding tubes, like KT 66 or 6L6 tubes in pushpull (e.g. Synthesis Audio A40 amp running KT 66s).  The EL 84 tube, which seems to be ubiquitous in “cheaper” tube amps should not be overlooked as some quite nice amps, like the Audio Note Oto runs this tube.

LM-845 Premium (2*30W) is a better choose for you. you should go to your local dealer to have a test listening.