Hartke LH series heads are superb. I just sold the LH1000 it is just entirely too heavy for easy transport so I got a MarkBass SD1200 love the MB. Now if both heads were like the MB very small and light weight, I would definitely still have the Hartke. Someone has to bust Larry's chops and ask him to make a class D amp like the MarkBass heads.

I WILL DEFINITELY OWN ANOTHER HARTKE IF HE MAKES THE LH1000 LIGHTWEIGHT AND PORTABLE!!!!!!
The Avatar will suit the LH500 just fine. IMO you will smile ear to ear with that setup. Good luck and enjoy a great sounding and versatile head.