Easy Tweak for preamp! - I have been playing with diy active shielded cables ( a la tesla) and tried it on the cortese power supply to pre cable - as it is a copper braid shield I just added a 12v wall wart power supply, 12v LED lamp and connected it to either end of the braided shield - switched polarity to get the best sound. I thought it a small but clear improvement - worth a try esp. if you have that stuff lying around
Cheers
Cheers