Its not recommended to run low impedance Speaker with High Impedance Amp there are hundreds of reasons said by expert. But with my knowledge(Gained in Forum) I shall let you some below.
1.Low impedance speaker would require more power amp,hence the amp get heaten up while running at high volume.
2.In case you dont have choice of using the combo, then dont turn the Volume knob above the average (Say 90 Degree)
3.The Live of Amp would get reduced gradually which its getting heaten Up, so be prepare for replacement.
In short the 4 Ohms speakers doesnt do any magic compared to 8 ohms, so Try avoiding the 4 Ohms (Which cannot be used in many amp as now by default the systems are supporting the 8 ohms Only)and in case you got then drive it with the suitable amp.