Hi Gijs!
Wiring speakers in parallell is not recommended. This would result in a lower impedance, again leading to your amplifier having troubles driving the speakers and risk burning out. One way to solve this is to connect them in series. This would increase the overall impedance, and is less likely to damage your components. Again, this is not Ideal both due to reduced sound quality and also lower volume. Going out of bounds from the amplifiers impedance range is always a risky option, but going for series would be a good way to start. DISCLAIMER: On your own risk, in the case with amps, and speakers there are very many variables. No way of telling for sure.
regarding your amplifier, it is hard to say the exact power output from it. Sometimes manufacturers state the power output during certain conditions such as "100w pr channel @8ohm" and so forth. when it only states 100w hifi amplifier, your guess is as good as mine. Would probably think that the true output would be >100w in most cases.
Xyfor got a reaction from BelgiumCastGijs in Multiple audio sources
