The sound signature of the original Aurisonics was very, very unique. They had huge bass and mid-bass shelves, and a restrained response from upper mid onward. I don't think there is anything close to that signature on the market. The FXA7 was far more conventional in response. If you call Fender, they will basically tell you they don't repair the older models. I tried, but they only replace the latest ones that are still under warranty. I am pinning some of my hopes to the new Xelento, which supposedly has a warm, muscular, and dynamic response. I tried the 64Audio Nio, and it has lots of sub-bass, and is otherwise a musical IEM, but the leading edge of the bass is mush. None of the Senns seem to better that. Although they are all very enjoyable. I also tried the Ikko OH10, and found it bassy, mostly in the sub-bass, and a delicate but thin treble. Midrange is quite recessed. Essentially, nothing like the Aurisonics/Fenders. So for now, I am stumped!