I just got my AES-3 DJH preamp back from Cary after having them install a headphone out. For a relatively small charge, they added a dedicated headphone out to my preamp. They also added a switch to engage the headphone out. Technically, I can't really say what else they did but I am very pleased with the early results. I look forward to comparing it to the Audio Valve RKV due in from Jan in the next week.