GA pilot reported a near miss during cruise with an opposite direction aircraft. Pilot took evasive action.

Narrative

We were on a VFR flight; flying directly to ZZZ and were under flight following from the ZZZ ATC. Our ADS-B was up and running. As we proceeded east to our destination airport we were directed to descend in steps. As we neared our destination; the advising controller gave us yet another descent; this time to 3000 feet. A target the we had been watching to the north of us was heading our way with a merging plot and we noted that his altitude was at the same altitude that we had been directed to descend to. After watching the bogie and determining that he was indeed heading to our plot of airspace; we elected to take some vertical separation on our own initiative. We observed the target pass directly beneath us and head east to our field. Had we continued our descent we would have inhabited the same point of airspace at the same time as our bogie. Nothing was said by the controller until the other aircraft was ahead of us by approximately a mile and a half when he was called out as 'traffic'.