I got my HX Stomp recently and it works fine as an interface on my PC.
I also got the Mooer Baby Bomb, for rehearsels and maybe Live Use and tried to go into a 4 Ohm Speakerbox, just to Test it out.
The way i connected everything was as follows:
Guitar in the Left Mono In, Connected the HX Stomp and Baby Bomb with a standard cable via the Left Mono Out of the HX Stomp and with another standard Cable out of the Baby Bomb into the jack of the Box.
Now, the Baby Bomb has an Output of 8/16 Ohms and like i said, the Speakerbox had just 4 Ohms.
Since i am not that stupid, i started with 0 Volume and gently, really gently pulled up the volume on the Baby Bomb ... I turned till 12 O' Clock, but still i couldnt get a Signal.