Hello Miner42:
If you upgrade the power cord start with the preamp. Do you have a local dealer? They should lend you a cord or 2 to try, hopefully ones that are broken-in. You would hear immediately if it makes a difference or not with the hum. Whether or not it helps the hum it should improve your overall sound especially if you're using a stock cord now. Then the can of worms if officially open. Power conditioner? Upgraded power outlet in the wall. Dedicated circuits. Nuclear reactor in the basement.... it's endless.
If you upgrade the power cord start with the preamp. Do you have a local dealer? They should lend you a cord or 2 to try, hopefully ones that are broken-in. You would hear immediately if it makes a difference or not with the hum. Whether or not it helps the hum it should improve your overall sound especially if you're using a stock cord now. Then the can of worms if officially open. Power conditioner? Upgraded power outlet in the wall. Dedicated circuits. Nuclear reactor in the basement.... it's endless.