Well, buying used is always an option, but you then run the risk of parts may need replacing, depending on age use, etc.. A new amp should give you more peace of mind. What does the BHSE offer over the KGST? I have listened to a couple of headphones on a BHSE, and I can say it is a great amp. I have also listened to the Carbon CC, which is an outstanding amp as well. I have yet to listen to any of the KG series and would love to compare them to some of the others I have listened to.