Looking at various fet-based inline preamps, they all tend to have rather high impedance. For example, popular Klark CT-1
Input impedance
7 kΩ
Maximum input level
-15 dBu
Output Impedance
2 k
Maximum gain
+25 dB, 10 kΩ load
Maximum output level
+10 dBu, 10 kΩ load
Let's...