I have to agree with the previous review. The board does not work properly and I do not see any way to find or fix the error.
At idle with no load connected, there is +/- 15 V at the terminals as specified. If I then connect a load that draws a current of 66 mA, the voltage at the positive terminal drops to 0. On the other hand, I can measure -15 V between ground and negative terminal.
Since I assumed that this was due to an overload, I ordered a second board half a year later, so that each channel has its own power supply, which then only has to supply 33mA.
To my surprise, the new board showed exactly the same characteristics. So both are not usable and in no way meet the stated specifications to supply 500mA at +/- 15V.
I must note that the Phonopre works fine with another dual psu. So the error has not its cause there.