Absolutely, I added a Mcintosh MC352 to my HK AVR7200. The sound improved dramatically. Think about the cost of your HK and divide it by the number of amps (7), not to mention all the bells and whistles with the HK. You're probably looking at around 100.00 per amp (guessing). It would be great if you could find a good amp to try, if not you could always take your receiver to an audio shop and have them hook it up to something for you.
Good luck
Good luck