Hooper signed permanently at Wednesday in the January transfer window, and he has already proved his worth to the Yorkshire club.
The former Celtic man notched twice in a 2-1 win over Birmingham City at the weekend, which has lifted Wednesday into the play-off places.
And Lees said of the striker: “Hooper’s class has shown throughout his career, it was just the case that he needed that chance to get fit and match sharp and show what he can do.
“He’s in great form at the moment and has been untouchable really.”
Hooper initially joined Wednesday on loan and he made a slow start to life at Hillsborough.
The 28-year-old did not score in any of his first seven appearances for the Owls, but he has been in wonderful form of late.
Hooper has now hit nine goals in his last 10 matches, and seems to have established his position as manager Carlos Carvalhal’s main striker.
Wednesday’s next match comes against Brentford on Saturday, and if they are able to beat Dean Smith’s side they could move up as high as fourth in the Championship table.