I am building my first preamp, and I have chosen the Aikido. Now my questions is, where to put the volume pot? Do I put it on the line in or do I put it on the line out? And if you could give an explanation on it, would be great. Thanks!
You want to keep the output impedance low and constant- inserting a pot there will cause a low, constant output impedance to be higher and dependent on volume control setting.
Also, placing it at the input means that your input stage can never be overloaded, because if it is becoming distorted by excess output from your source you can simply attenuate it by turning the volume control down.