Elad770, to rule out a faulty headphone plug from Amazon, try using a regular 1/4 inch plug from a patch chord end while the Genos is playing through your speakers. The sound should cut out after you insert the patch chord. If the sound cuts out, the Amazon plug is no good. If the sound stays on, then the Genos jack is faulty.
Note If you insert a mono 1/4 inch plug, only one side will cut out of the speakers. Perhaps someone can comment on this. A stereo plug would definitely cut out all sound from your speakers.