I can't find any real specs on that mixer-amp. They don't mention what minimum impedance it can handle or what impedance the 600 watt is into (8 transistors is not 8 ohms). The 600 watts is peak power so there is no way to know how much power it really has. Maybe 100 watts watts or so? Most likely it will be fine but be careful not to damage the speakers by playing them too loud. The woofers could be rebuilt but the mid and tweeter are probably no longer available.
An inline fuse might save you from blowing the speakers.