Compare the picture below to your DAC, if yours have the red circled parts on the small
circuit board against the metal chassis, please follow the instructions below to make your
modification.
Version #1’s instruction DOES NOT APPLY to your unit.
Before:
As a DAC, the two black jumpers are connected at factory as 1+2 and a+b. If you cannot
read the printing on the circuit board, use a magnifying glass – this is very important to
connect the jumpers to the right place.
After: (using the unit as a pre-amplifier)
Use a small tweezer to pull off the two black jumpers and connect one as
2+3 and the
other one as b+c.
This will allow the volume control to be included in the circuit to use the unit as a
preamp.
Remember to set your volume to lowest before you turn it back on then
adjust the volume gradually. If you leave the volume at full when turning it on, you
may accidentally damage your speakers.
Version #3:
This one is nearly identical to Version #2, except the above jumper connections are done
at 1+2 and a+b by physical soldering at factory so there are no black jumpers to move
around. (see picture below)
Factory preset the jumpers as
1+2 and a+b for TubeDAC.