I agree with you Alan. If I were changing anything I would do the op amp input resistors rather than the ones feeding the mixer. If I am reading the schematic correctly both are involved in setting the op amp gain but the ones before the mixer may also? have some effect on swamping the switching load. After the mixer is a high impedance point and only affects gain set...... I think!
My plan when I have test time is to set a baseline level for the system and then tack a second 10 ohm resister across each of R31 and 30 and then check the system gain and MDS. I will report back the results.
If someone has already done this please speak up and save me the trouble.... :-)
Warren Allgyer
9V1TD
Warren Allgyer