From panel:

1. 6.5mm headphone output socket: connect to big headphone , like hd600, akg k701/702, dt880/dt990 ....

2. 3.5mm earphone output socket: connect to IEM and other earphone, the output is smaller than the 6.5mm , because we put a 33ohm resistor between the 6.5mm socket and the 3.5mm socket! in case the high output damage the small earphone!

Back panel:

1. RCA output socket : the line out from E7 will be amplified by OPA2134 to standard 2V rms line out signal. the output level is constant!

2. 3.5mm output socket: the line out from E7 is send to the volume control and them amplified by another OPA2134, so the output level is adjustable, it is designed to connect to some pure amplifier which have not volume control, in this case, the E9 can work as a pre amplifer!