Shure SM7B and a MOTU M2: how much gain does the M2 actually have?
MOTU publishes an EIN of −129 dBu for this preamp and no gain range at all. Speech asks the SM7B for 58 dB. This page says what can honestly be concluded from that, and what cannot.
Short answer: nobody outside MOTU knows, because MOTU does not publish it — and this page will not invent the number.
What is known: at 85 dB SPL a hand away, the SM7B delivers about −65.8 dBu. The M2's converter clips at +10 dBu, so a −18 dBFS target needs 58 dB of preamp gain. What is not known is how far the M2's knob goes. Its spec sheet lists an EIN of −129 dBu, a +10 dBu maximum input, 192 kHz, a 3.27 V headphone output — and no gain range. The calculator on this page therefore falls back to an assumed 50 dB and marks the result as assumed. Treat that flag as the answer: an assumption, not a measurement.
If you already own the M2, you can settle it in two minutes. Speak at your normal level and distance, turn the gain fully up, and read the meter. If peaks land near −18 dBFS, you have all the gain you need. If they land at −26, you are 8 dB short and an inline booster fixes it.
The thing worth knowing: EIN is not gain, and it is quoted as if it were. Equivalent Input Noise is measured with the gain at maximum and a 150 Ω resistor on the input; it tells you how quiet the preamp is when it is working hardest, not how far it travels. An interface can have a class-leading EIN and still run out of range on a broadcast dynamic. When a manufacturer publishes the noise figure and withholds the gain figure, the honest reading is that the gain figure is not the one they wanted printed.