@atmasphere Thanks Ralph, I've just been cheating by using the calculator at vh audio (https://www.v-cap.com/coupling-capacitor-calculator.php). Fortunately because the pre is basically an advanced kit, I do have some ideas of what range is normal for use.
I also just leaned that I can change the resistor on my amplifier (diy first watt f4s and sit3s) to a any value within a decent range. Moved both up to a 200k input impedance to allow for the use of smaller caps.
I also just leaned that I can change the resistor on my amplifier (diy first watt f4s and sit3s) to a any value within a decent range. Moved both up to a 200k input impedance to allow for the use of smaller caps.