DAC Op amp roll ZD3 or ZA3?

[LBUCCI]

I have a ZD3 going into a ZA3 in stereo via XLR. Everyone talks about sparkos op amps being a major improvement. The question is do I swap the op amp(s) in the ZD3 or ZA3? If it's both, that's just an astronomical cost and likely worth doing. So swap the DAC or the amp op amps? Thoughts?

 

[Infinity Poodle]

I've heard that swapping the opamps in the ZD3 actually decreases sound quality, but I am definitely NOT an expert. There is a video on Passion for Sound (Youtube) where he mentions this. Anyone else have any thoughts as I have the same question as LBUCCI? BTW, swapping the L/R opamps in the ZA3 definitely improves audio quality, most seem to recommend the Sparkos, Oracle II-02's or Muse 02's as far as I know. I've tried the cheaper OPA1656's and the have been great so far. The above Youtuber also suggests the Burson V7 Vivids for the ZA3 as he says that the Sparkos are a little too "smooth" for the ZA3.