Your Denon should have it's own test tones built in. At least mine does. I had the same frustration with the Avia disk for the sub but the Denon sub tone stays on until you turn it off.

I also had a weird, still unexplained, issue with the Avia sub tone where it freaked out my meter and it kept jumping up and down by up to 10 db. I am aware that the disk cycles between sub only and sub plus a speaker to check for phase but this happened continually during the sub only part.

I thought maybe I was running too hot or something but using the Denon's test tone resulted in a smooth, even reading that I was able to calibrate with.

With great power comes Awesome irresponsibility.