Did you change the sensitivity to -10 dBV? That plus 9 dB gain is not enough? Then your guitar is more than 17 dB lower in volume than the hottest ones.

A boost pedal with only 1 kOhm input impedance - can not be, you must have misread some tech spec.

The Babyface Pro includes a hidden digital gain of +/-20 dB, so you could easily raise the input level by up to 20 dB. Only for monitoring, or also for the recorded signal (Settings dialog: check mark the option DSP - EQ for Record).

How to add digital gain? Activate the EQ, set Band 3 to the lowest value of 20 Hz, Q to the lowest value of 0.7. When you change the gain of Band 3 the whole frequency range from 50 Hz up to 22 kHz will be raised. The last pic shows the result as frequency measurement when setting it to +10 dB, +15 dB and +20 dB.

A guitar does not have frequencies below 50 Hz, but if you want to have it perfectly linear, check the +15 dB example again: here the same settings were done in Band 1. This removes any low frequency drop. Easy to check as the frequency graphics in TM FX EQ show the same.