My intuition would lead me toward the SIT monoblocks given your efficient speakers.I`m sure the Pass amp would sound very good .Based on reviews if seems the SIT-1 is 'special' and with its ultra simple,single gain stage clas A design is likely a purer,more natural and transparent sound.
Could be a case of very good amp compared to a sublime amplifier,Nelson Pass seems especially proud of this particular First Watt amplifier. If I were to venture to a SS amp the SIT-1 would be my destination. Good luck to you.
Gon member 213 cobra has first hand experience with both of these amplifiers and he thought the SIT-1 were superior.
Regards,