Shure SM7B with SSL 2 MkII: are 64 dB of gain enough?
Enough, with 7 dB in hand — which is more margin than a Scarlett 2i2 4th Gen leaves, although the Scarlett has 5 dB more gain on paper. Comparing maximum gain figures without the clipping points that go with them ranks these two interfaces backwards.
Yes — 57 dB needed against 64 available, so 7 dB in hand at a normal speaking level.
The arithmetic. −59 dBV/Pa at 85 dB SPL is −65.78 dBu at the XLR. The SSL 2 MkII clips its mic input at 9.7 dBu, so landing on −18 dBFS asks for 9.7 − 18 + 65.78 = 57 dB. Published maximum: 64 dB.
The comparison that makes this page worth a page. The same microphone, the same voice, three popular interfaces:
| Interface | Clips at | Gain needed | Gain it has | Margin |
|---|---|---|---|---|
| SSL 2 MkII | +9.7 dBu | 57 dB | 64 dB | +7 dB |
| Scarlett 2i2 4th Gen | +16 dBu | 64 dB | 69 dB | +5 dB |
| Audient iD4 MkII | +12 dBu | 60 dB | 58 dB | −2 dB |
The SSL has the smallest gain figure of the three and the largest margin. Its input ceiling sits 6.3 dB lower than the Scarlett's, and every decibel of ceiling is a decibel of gain the chain has to supply.
Where it does run out. At 75 dB SPL the requirement rises to 67 dB and this interface is 3 dB short — enough for the calculator to start recommending an inline booster. So the honest verdict is «yes for a voice at a hand's distance, no for a voice at arm's length», which is a statement about microphone technique as much as about the box.
The pearl. The SSL 2 MkII also carries the lowest published equivalent input noise in our catalogue, −130.5 dBu against −127 dBu on the Scarlett 2i2 4th Gen. That matters precisely here, at the top of the gain range where a quiet dynamic lives: the two interfaces are ranked one way by the number on the box and the other way by both numbers that decide the result.