I'm going a different path. I've modded some of the caps on the dac and analogue pcb's. The stock diodes are already fast diodes and there are snubbers across them to reduce ringing so there should be little to be gained by swapping them out.
The output stage does use a TL072 op-amp which has a jfet input but I'm yet to fully investigate the role that this device plays in the analogue stage. (Note: Good performance can be obtained from this op-amp by bootstrapping the supplies or feeding from a low Z source to mitigate the non linear input capacitance)
I also intend to reduce the earth inductance between the DAC and PSU pcb's which are connected via a long pinned connector strip.
Thus far, upgrading the 10000uF 6.3V caps on the DAC pcb to Cerafine's + adding Wima mkt decoupling caps in the analogue supply has made a substantial improvement. My next mod is to upgrade the 78XX/79XX regulators that feed the analogue stage.
The output stage does use a TL072 op-amp which has a jfet input but I'm yet to fully investigate the role that this device plays in the analogue stage. (Note: Good performance can be obtained from this op-amp by bootstrapping the supplies or feeding from a low Z source to mitigate the non linear input capacitance)
I also intend to reduce the earth inductance between the DAC and PSU pcb's which are connected via a long pinned connector strip.
Thus far, upgrading the 10000uF 6.3V caps on the DAC pcb to Cerafine's + adding Wima mkt decoupling caps in the analogue supply has made a substantial improvement. My next mod is to upgrade the 78XX/79XX regulators that feed the analogue stage.