I just accidentaly plugged my M160 into a preamp with phantom power on today. Nothing happed, mic is working.

Thank goodness it was a pleasant experience. Don't make it a habit.

As the previous contributions to this thread suggest, there’s very likely a difference between connecting the mic’s xlr with the phantom power already on (ie hot plugging) versus making the xlr connection first…and then turning on the phantom P48.

Again, The cautions are:

1. That the P48 circuit has been implemented correctly. This would be true in most modern commercial products.

2. That the mic cable has been properly wired, without grounding Pin 2 or Pin 3.

3. That the mic itself is wired correctly internally, also without ground on Pin 2 or Pin 3.

If any of the above are NOT true, there will be voltage applied across the mic, which if there is enough current supplied, can cause the ribbon to be forced into excursion beyond its design limits, and put a permanent stretch in it's pleats.

If all of the above ARE true (which they would be in practically every case), there will be no damage to the mic. It’s one of the primary design goals of P48 in the first place, and why it was adopted as a standard in deference to differential power schemes.

We all should try not to connect a ribbon with phantom hot, just like we use a seatbelt every time we drive. But forgetting doesn’t usually result in disaster either.

Can a multimeter be used to make sure that a microphone (especially a passive ribbon mic) is wired correctly before connecting it to anything?

A multimeter on the resistance (Ohms) setting injects a small DC voltage into the device under test then measures the voltage drop across a known resistor inside the meter. What's a "small DC voltage?" It depends on the meter, and the range is pretty huge. Modern 3 1/2 digit DMMs might inject 0.1V, but older meters have been known to inject up to 4 volts or more. This is also something that is not specified clearly in meter manuals, so the easiest way to know what your meter's test voltage is would be to measure the voltage produced by one meter set to Ohms and connected across a 100 or 200 ohm resistor with a second volt meter.

Needless to say, you don't want to squirt a lot of DC back into your ribbon mic. But how much is too much would vary with mic design. Generally, it should not be a problem with modern digital meters. But again, we like to be cautious too.

There are a few tests you can make with any multimeter, being careful, of course. You can measure the resistance from Pin 1 to Pin 2 (it should be very high or open), Pin 1 to Pin 3 (should also be very high or open). You might also want to check between the connector shell and Pin 2 or Pin 3. All of the above tests will most likely read either an open or a short. A short is bad.

You wouldn't want to purposely, or accidentally put the meter between Pin 2 and Pin 3 without understanding your meter and it's test voltage.

You could also open up the XLR connectors to see what's what.