It's generally good practice to disable phantom power if it isn't required. However, almost all modern, non-phantom powered, microphones will not be harmed if phantom power is applied to them under normal conditions. This is especially true for dynamic mics such as the SM57, which will not be affected by the presence of phantom power. That being said, there are a few situations which are more likely to cause damage to microphones:

Incorrectly Wired Microphone Cables

If ground is accidentally wired, or shorted, to either of the other pins, phantom power can cause damage to ribbon microphones. This can be avoided by using cables from a reputable manufacturer and replacing cables where the connector is visibly worn out.

Applying Phantom Power Across a Patchbay

Patch cables use TRS plugs, presenting all three conductors (tip, ring, and sleeve) within a single in-line connector. When a cable is inserted into a patch point, the connections are momentarily shorted. This can create a situation where phantom power is applied to the ground pin of an attached microphone, which can cause damage to it. If you're using a patchbay with your interface, it's best to disable phantom power before doing any patching.

The Microphone is Unbalanced (High Impedance)

Any mic wired for unbalanced operation will be damaged by phantom power (typically vintage ribbon mics). If you're using such a mic, care should be taken to not apply phantom power to it (using a product like the Triton Phantom Blocker will help here).

In addition to the above, if you're connecting something that's not designed to be connected to a mic preamp; it may be damaged by phantom power. We would recommend avoiding this situation by only using the XLR connector for microphone, or other phantom powered equipment, whilst using the jack input for line/instrument level equipment.

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