I have read a few people have been unable to find satisfying heavy tones on the hd500.
I feel its a great unit, the tone may be elusive, but it is there if you are patient.
I am uploading my preset with a few variations so anyone may use it. No guarantee it will work for you but you may be able to use the hybrid pre/full technique to find what you need.
there are 4 variatons 2 dialed for emg 707 2 for duncan ahb3. They are all pretty close but there are differences in gain levels
Patches are called 'Caution treadplate'
Id love to head some similar or better tones.
Thanks for the upload.
I don't have an HD anymore but would love to hear some clips!