Quote:

And how would I know if I was pushing the reciever to much?



Raspiness and harshness for one. It may sound like I'm trying to be funny but I'm really not. Unless you have an oscilloscope to see clipped waveforms, your ears are the best judge.

Does the tone control help? If so, you're likely not over-driving it.

You said "sometimes" which leads be to believe that your HK's 75W are being taken to task during movies that have large dynamics. Or, maybe you have a damaged tweeter or amplifier channel.

Turn your speakers off and then turn each one on all by its lonesome. Any raspiness or kazooing from one and not another could be an indication of tweeter damage. Replace that speaker with another and if the kazooing moves with the speaker, tweeter damage is probable. If not, that particular HK channel has a problem.