If Lugnut is right... (I assumed the LK 100 was a a stereo amp...) then all LINN mono cards for the 5120 or Ekwal will fit and work to spec..
Call Linn in Jacksonville @ 888-671-LINN to confirm....
FWIW I have the mono cards also offered on Agon for $150/pair... mine are broken in, which will take you 200-300 hours with newer ones.... just an observation...