I've had an M-Audio Delta 66 w/ Omni IO breakout box for around 10 years.
The Omni IO went crap, a couple weeks ago, and I just replaced it with a Focusrite Saffire Pro 14.
I did some recording (AudioTechnica AT4033SE), on the new Saffire, and I had to crank the pre-amp up a lot higher than I did on the Omni.
Given the same start and end points, I would keep the Omni at around 10:00 and the Saffire had to be at around 2:00.
Is there a reason for this?

Here are some specs, for each (maybe the numbers show an obvious difference, but I'm not that smart):
Omni IO

• Measured D/A specs: 103dB (A-weighted) dynamic range, 0.0015% THD @ 0dBFS
• Measured A/D specs: 99dB (A-weighted) dynamic range, 0.0023% THD @ 0dBFS

• Low impedance mic inputs provide 66dB of gain and utilize M Audio 's critically acclaimed DMP2 pre-amp technology. They are switchable to hi-impedance instrument inputs with 46dB of gain,ideal for electric/acoustic guitars
• The Omni Mic/Inst pre-amp has a frequency response of 10Hz to 200kHz,low THD of .0009%,with a dynamic range of 130dB

Saffire 14

• Gain Range: +13dB to +60dB
• Maximum Headroom +8dBu
• THD+N: 0.001% (measured at 1kHz with a 20Hz/22kHz bandpass filter)
• Noise EIN: 124dB analog to digital (measured at 60dB of gain with 150-ohm termination - 20Hz/22kHz bandpass filter)
• Input Impedance: 2k ohm

Is there something that explains the difference in pre-amp level required to get similar recording levels?
The mic and vocal is always the same and, once I get them set, I rarely change knob positions.
JJ