Since the lingDAC has only I2S input I need a quick and dirty way to provide the rest of the infrastructure to get something to listen to. Taobao comes to the rescue as on there are a few DACs based on TDA1387 which have digital front-ends on them and enough room inside to hide a filter/IV board. Here is the cheapest one : 4 * TDA1387 USB DAC. I have bought my first two of these with cases but the seller also sells just the PCB as a kit. My gf persuaded him to solder on the CM108 as that's a little tricky to do by hand, so we have more on order at the princely sum of 44rmb for just the PCB and kit of parts.

Firstly its necessary to make some modifications to the board to accept the lingDAC filter/IV stage. Here's a picture of the mods beginning -

The parts just to the north of the RCA outs are passive IV/filter components which the lingDAC PCB will replace. So they must come out - here I've pulled out caps (2n2 and 220p) and the output coupling caps (CR, CL) which were electrolytics. The 1ks are the I/V resistors, we need to change those to 680ohm.

The next set of mods are to the power supply as the stock board has inadequate filtering on the 5V USB rail.