8 individual missiles, even if you launched them all at the same time (which the Lanzhou could not), would not be able to overcome the Lassen's missile defense capability. Even supersonic missiles like YJ-12 and YJ-18 can be dealt with by today's technology. Against an individual Aegis destroyer I would just go ahead and launch several dozen antiship missiles all at approximately the same time and vector them in from as many angles as possible. This prevents the SPG-62 fire control radars from easily tap-dancing from one target to another and forces them to cover larger arcs of fire; this would similarly affect the Phalanx CIWS. Without an E-2C/D flying overhead, the Lassen would be more easily overwhelmed by a smaller saturation attack as it could not engage incoming missiles until the SPY-1D's could see them. If there were an AWACS overhead, it might take double (or more) missiles to overwhelm the Lassen, as it could engage the incoming missiles much earlier.