To everyone: Vorzuge contacted me to tell me that they will lower the gain for free if you want it lowered.
The um3X are very sensitive earphones, but not as bad as the UM2 or the SE530 are. Still, depending on how loud you listen to music, they will probably be close to the comfort line. I know a lot of people here in Japan who have no problem with sensitive earphones and the Vorzuge, but those who do, do.
As for burn in, just listen and enjoy. Don't worry, the more you enjoy, the more things will settle.
I am glad you enjoyed the review. I worked very hard on it. I believe the Vorzuge is one of the most interesting and incredible amps on the market now primarily because of its size, low Ω output, rich mid section, and with the DUO, the EQ. It is also made very very well.
The UE Superfi EB is very very sensitive, one of the most sensitive earphones in the world in fact. The Vorzuge's current version is low enough that you will probably be fine, but if not, you can of course get Vorzuge to adjust your gain. They do this for free.
shigzeo after reading your reviews has really made me very interested in the VorzAMPduo...
for myself currently i'm using my ipod classic 5.5G->voyager->UE Superfi EB(reshelled).
i'm a bass lover myself as i leave the contour switch on all the time.
from your experience do you think the VorzAMPduo will be too loud for my IEM?