Most amps will clip at full volume, especially when the gain on a preamp is involved. I agree with Mrdecibel on setting the amp at full volume. There are no rules out there about where a volume control should be set at.
I've owned 3 of these amps. Very good for the money. They do have a thermal protection if you are over-driving them, if I recall. Also, since you are running 4 ohms, make sure you are NOT using more than one set of speakers. Even though you can hook up more pairs, it will take you impedance way too low. I've never met a Yamaha that would handle less than 4 ohms. Are these speakers running lower than 4 ohms? You may need to have the speakers checked?
Do you get the same issues in class A and in A/B? The amp should run fairly hot in class A. Most class A amps run very hot. Enjoy it. You just got 90% of a Threshold for 25% of the cost (in my opinion).
I've owned 3 of these amps. Very good for the money. They do have a thermal protection if you are over-driving them, if I recall. Also, since you are running 4 ohms, make sure you are NOT using more than one set of speakers. Even though you can hook up more pairs, it will take you impedance way too low. I've never met a Yamaha that would handle less than 4 ohms. Are these speakers running lower than 4 ohms? You may need to have the speakers checked?
Do you get the same issues in class A and in A/B? The amp should run fairly hot in class A. Most class A amps run very hot. Enjoy it. You just got 90% of a Threshold for 25% of the cost (in my opinion).