Rev, you certainly can. My rears are 8ohm in-ceiling speakers and my fronts are 6 ohm. So specifically, you can have different impedance speakers on the same amp.
In my opinion, more of an issue is the timbre match of the speakers as opposed to the Ohms. If the speakers are from the same manufacturer, I wouldn't think twice about it.
In my opinion, more of an issue is the timbre match of the speakers as opposed to the Ohms. If the speakers are from the same manufacturer, I wouldn't think twice about it.