I have a Willsenton R8 in my second system right now, and it's terrific. It's not better than the Atma-Sphere gear in my main rig, but it's perfect for the living room.
Everyone is correct that you need to give the Pass some break-in before you can make a rational judgment. I'm not familiar with the INT-25 but I've owned a couple of Pass clone amps and it should sound great. That doesn't mean you'll necessarily like it better than the R8, regardless of the price difference.
After a reasonable break-in period for the Pass, trust your ears.