Your amp will put out power at any impedance shown to it from very low to very high - it does not 'put out 4 ohms' for instance but rather delivers XXXwatts when a 4 ohm load is connected to it.
Since the amp is rated down to 2 ohms anything below that may damage it but on the top end there really is no limit - the amplifier just keeps making less power as the impedance goes up so most people try to keep it to a nominal 8 ohms.