Just about any amplifier will run your speakers, that 86db is for 1 watt of power at 1 metre, 5 Watts will be at around 88db at 1 metre away from the the speaker
That rating of 100w is simply there so that you can run the speaker safety at high volumes without damage to either. It's very rare that anyone needs to go full on, any amplifier with a good quality power supply will be suitable up to modest volumes. It can then supply the current that your speakers need