There are two different Phoenix connectors on the back of the speaker. One is for bi-amping and has six connections. Two of them are unused and and the other four connections are for high frequency +/- and low frequency +/-.
There is another separate connector if you want to use the built-in crossover. It just has a positive and a negative connection that you would connect to the positive and negative of most normal amps. You could use the Topping amp with that connection. You would only use the bi-amp connection if you have an external crossover.
When using a single amp channel to power the speaker I would put a volume limiter on the receiver or processor. Most receivers and processors have a max volume limit and I would set that so one couldn't accidentally blow the speaker.