I am late to this party but I have a LAP 150 MKII just upgraded to Signature edition. I received my preamp back in August so I now have it broken in. The upgrade added a lot of needed bass as well as overall better performance. My Savoys have 4 12" woofers per speaker and I can feel the difference with the upgrade. Jug did tune the impedance to match my Spectron amps. I am not sure what made the difference but I am quite happy with results. I am surprised you do not have bass from your LA 150SE preamp. I know of 2 things which also helped my bass were Elrod power cords and short Spectron Remote Sense Signature speaker cables. This all added up to better bass. I have not tried either amp but Pass was on my list so I cant help you there.
