I had a LM-216ia. It was not quiet -- it had an audible hum with my Focal Aria 936's and eventually sold it because I could not stand the hum.
I also put it on a scope and measured it. The amp had low THD, but the noise was on the order or a few mV. The transformers had a resonance around 250kHz, which manifested itself in a lot of ringing and overshoot when I tested the amp with square waves.
My take on Line Magnetic is: their amps look cool, but I really did not like their transformers and the humming.