You read first and make sure the amp will be all right. You have a manual? Find one. I tap what sound the best. Then I check for heat. Smoke is to late.. :-)
Most amps if you screw up they will pop a fuse if the load is to heavy.
I like using an 8 ohm tap for 6-12 ohms. But I use the same type of drivers. Small planars, and ribbons. Easy loads. I can't get a class D to heat up. An AB valves amp runs a lot cooler behind very efficient light driver material. Nothing is heavy about planars or ribbons. Magnets?
Your bouncing around a bit. Get a heat gun, it will tell you a lot.. Check the heat index. Rule of thumb, cooler is better, and listen..