Let me copy only the subject not yet solve, all those in block is answer from P-A in email;
2) When I first time test the board, I tried to changing R1/E1 (56K) as loading impedance and left R3 blank, omit J1/J3, direct changing the loading resistor by a dip 8 way switch (8 resistors on dip, from 10R to 47K), then I don't need to switch MM/MC by J1/J3 but only switch the dip to match the loading impedance, however the QSXM2 sounds like overloaded with highly distortion sound, I have no idea where goes wrong, any suggestion?
2 Did you change the gain also? J2
2) No matter how to set J2, the sound also distorted, and very funny is when I switch off the power, without lift up the tonearm, the sound become normal at the very last 1 or 2 second, while the filter caps on JSR04 almost run out of electricity.
2 The same in both channels?
Yes, both channels.
Can your chosen opamps handle +- 18V?
How high is your output level?
You could check the currents through the stages.
Which transistors have you used, pinning?
I use MAX420 and OP07 as refer to the files.
I have not check the output level.
Will check the currents within days.
I built 2 boards, one use all BC550C/560C, another all SMD type, both have the same problem, this is why I have no idea where goes wrong.
Can you rule out the cartridge itself?
Is the sound distorted regardless of sound level?
I think it's a good idea to check all critical cuurents through each stage. Maybe you have taken the wrong value somewhere?