As already written by MtCa, this is possible.
You can find the manual on the Klipsch website. It also describes and illustrates how to connect it.
https://assets.klipsch.com/product-ma...

I myself have a sub right and left output on my receiver. One of the outputs is labelled "Sub (Mono)". I connected the cable from this output to the LINE IN LEFT/LFE subwoofer input of the R-101SW.

On my receiver, I then had to set it to Sub (Mono) in the settings. This should not be necessary for you, as you only have one output on the Wiim Amp.
Either way, it makes sense to read the manual for the receiver and the subwoofer. If necessary, you can also adjust other things such as bass level etc. on the receiver to get a good sound result.
On my receiver, for example, I first had to activate the SUB mono output in order for a signal to come out. And then set the bass level and bass phase adjustment.
So read the Wiim Amp manual to find out what settings there are for external sub-woofers.

Yes, that works. You can simply use one of the 2 cinch inputs on the sub (typical for home cinema, the LFE channel (mono)). In general, a subwoofer is only ever mono (only 1 channel). The two cinch inputs (stereo) on this subwoofer are then also routed internally to a single channel. From experience with the Klipsch, I can confirm that both types of use (i.e. LFE/mono or stereo) sound identical and are equally loud. So in a nutshell: Simply run a cinch cable from the wiim sub pre-out (cinch output for subwoofer) to the one channel on the cinch inputs of the Klipsch (usually the left channel, but that's what it says). Hope that helps!

Thank you! That helps! Greetings JH