So opinions seem to vary and with no real consensus it probably means I should consider getting a used DDC and if it doesn't improve things in a worthwhile way, I can always resell it at minimal to no loss.
That was exactly my plan, but after hearing my Pegasus with the i2S connection there was no way the Iris was going anywhere. Lots of diverse opinions here, but I’m the only one actually using the same DAC as you so perhaps you might consider that for what it’s worth.