Wiring speakers to inputs? That's called a dynamic microphone. I've never used a 12 inch diameter microphone? You take the output of amplifiers and plug them in to the input of speakers. This is sort of like learning the difference between left & right. But I won't write about that here because someone might be left out? Now hold up your right hand. Your other right. Good. Here goes.

Connecting two speakers together, whether in series or parallel should do nothing to harm the speaker. 8 ohm speakers in parallel is equal to 4 ohms. Where as in series, you have 16 ohms. Nothing wrong with either of those connection schemes. And the amplifiers, typically used in control rooms can support a short to an open circuit without causing damage. That's most good amplifiers. Not all. Some well blow right up if not properly terminated into the proper loads.

If you have a VOM multimeter, try reading the resistance across the speaker terminals, without them being connected to anything. You'll utilize Rx1, since 8 ohms is nearly a short. If you see no reading on the meter, the voice coil has blown. It's dead. You should be able to observe a nearly full-scale meter deflection if the speaker voice coil is intact. Some speakers are worth repairing. Cheap speakers are not. That, not being a particularly fabulous speaker? You might consider replacing it? But you'll find that efficiency levels between different manufacturers of speakers are different. Some will produce more sound than others with the same amount of input power.

There aren't too many ways to blow up low-frequency drivers. A typical misconception is if the speaker is rated at 50 W? You don't use a 50 W or lower power amplifier. On the contrary. You'd want a 150 W amplifier, or higher. Why? Because clean power that exceeds the speakers ratings is perfectly fine up to about a factor of four times greater to five times greater than the speaker is rated for continuous power. Peak's are not continuous. When you exceed that continuous power rating, yup, you're going to kill them. But it's a confusing state of affairs. For instance, an underpowered amplifier is more apt to destroy a speaker than any overpowered amplifier. Why is that? Well, it's because if the amplifier is underpowered and begins to clip. It's going to cause enormous amounts of supersonic harmonics (a.k.a. harmonic distortion) sent to the speakers, that will quickly heat up the speakers voice coil causing it to fail. Speaker crossovers attempt to route certain frequencies to the speakers designed for those frequencies. But with a clipped amplifier, everything suffers. So you can never have too much power but you can have too little. A mistake often made by those that don't realize that speaker power specifications are for continuous power not peaks. In fact my JBL 4310/11/12's are all rated at 50 W, continuous, if you can take it. They've always been driven with 150 to 200 W per channel, each! And I have a tendency to crank them up. Never blew one yet in over 30 years. Neither should you.

Power debacle
Ms. Remy Ann David

Remy is right when it comes to Pa or Monitors.
If we are talking Tube guitar amps or even solid state Guitar amps Your Speaker wattage should be greater than the Amp wattage and always match the load( impedance)