The Lenco MC-160 is designed specifically for the included speakers and has an output power of 2x 10 watts. This means that the system does not have enough power to drive larger speakers directly.
If you do want to use more powerful speakers, we recommend connecting an external amplifier system. This can be done via the MC-160's headphone jack (AUX-Out). Connect this output to an external amplifier to which you can then connect your more powerful speakers.