The opamps in this Directstream DAC are special high frequency video opamps. The ones Danny is speaking of from Sparkos is a replacement for standard opamps (not compatible at all with the DS). We make our own discrete opamps for other equipment.
We have tested other compatible opamps however the ones in the DS work the best especially when the DC offset is fixed. We have spent 1.000’s of hours working with the Directstream MK1 DAC and feel it’s at it’s best with the Limited Edition upgrade. We even tried using a custom opamp output stage instead of our transformers and it didn’t sound even close to what have now. Ted designed these DS DAC’s to use an audio transformer for a reason.