Johnson Wagner, a two-time winner this year, carded a 1-under 70 and is alone in second at minus-8. Wagner had shared the lead after round one with Jess Daley.
Daley managed an even-par 71 Friday. He was joined at 7-under-par 135 by last week's winner Kevin Stadler, Steve Wheatcroft, Richard Johnson and Jason Buha.
Adamonis opened with five straight pars before two-putting for birdie on the sixth. He made it two straight as he birdied the seventh to move to minus-7.
The 33-year-old drained back-to-back birdies from the 10th. Adamonis moved to 10-under with a 12-foot birdie putt on the par-4 13th.
Adamonis knocked his approach to 12-feet at the last and poured that putt in to take his first 36-hole lead on the Nationwide Tour.
'I played really well. I had a great day ball-striking,' said Adamonis, who is going for his first win on tour. 'I putted a little better on the back nine. I made four nice putts, actually five. The front nine I didn't really make anything.'
Wagner played the back nine first Friday. He birdied 10, but gave that stroke right back with a bogey on 11. Wagner atoned for that error as he drained a 25-footer for birdie at 12.
The 26-year-old tripped to a bogey on 17 to make the turn at minus-7. Wagner birdied one and three around the turn. However, he gave both of those shots right back with bogeys on two and four.
Wagner again got to 8 under when he birdied the par-3 seventh. He parred his final two holes to remain there.
'I putted really well on my opening nine. Every putt I hit had a chance to go in - they all just seemed to lip out,' Wagner said. 'I got on a little birdie- bogey string when I turned. I didn't play nearly as solid as Thursday, but it was a good day.'
Matt Weibring and Tyler Williamson each posted rounds of 5-under 66 to move to 6-under-par 136. They share eighth place with Rich Barcelo (68), Joe Daley (67), Bradley Hughes (69) and John Mallinger (70).
The cut line fell at 2-under-par 140 with 62 players advancing to the weekend.