Electret microphone to USB soundcard
Remove R1 and C3. Feed the +9V through a resistor, a good resistance is somewhere between 2kOhm and 20kOhm. Start tests with 10kOhm. Higher resistance increases the sensitivity to some degree as long as it's not too high. Too high resistance causes distortion.
If it happens that you do not use a battery as your 9V source there's a possibility for fatal errors. Many power supplies are not isolated, even mains AC input power supplies can have a capacitive connection between the mains AC input and the output whic output 50% of the mains AC voltage through a big capacitor. Many of them have galvanic contact between the output and the protective ground of the mains AC plug.