In that case, I would guess that the synthetic liners are either doing their job and wicking moisture away from your feet and making them feel dry and warm regardless of the wool sock outside of them, or somewhat doing their job and making them feel damp and warmish regardless of the wool sock outside of them. I have not used liners in either so I cannot compare personal experience.
However, I have used darn tough. smart wool, first lite, yak, and camel wool socks all without synthetic liners and can say there is a significant difference in warmth/dry feeling with the 100% yak and camel sock as compared to merino blends. I suspect that they feel warmer because my feet feel drier.
If the liners improve the damp feeling of the merino blend socks, I might have to give them a try.