While Newbee is correct with his power table, I would also add that you do not have to stay that close to the 120 WPC speaker manufacturer recommendation, to answer your question.
I would recommend that you use a higher powered amp than the 120 wpc factory recommendation. The reason being that most speaker damage occurs from over-driving an under-powered amp past it's performance envelope, causing an unstable amplifier condition called clipping. Much more speaker damage occurs during clipping, rarely is a speaker damaged with too much 'clean' power. In other words, you run a much greater risk of damaging your speakers with a 50 WPC amp than you do with a 150 WPC amp.
You should be safe with a 150-200 WPC amp, or more if you choose.
Cheers,
John
I would recommend that you use a higher powered amp than the 120 wpc factory recommendation. The reason being that most speaker damage occurs from over-driving an under-powered amp past it's performance envelope, causing an unstable amplifier condition called clipping. Much more speaker damage occurs during clipping, rarely is a speaker damaged with too much 'clean' power. In other words, you run a much greater risk of damaging your speakers with a 50 WPC amp than you do with a 150 WPC amp.
You should be safe with a 150-200 WPC amp, or more if you choose.
Cheers,
John