If I understand correctly, I have the option to put a SPARKOS LABS Pro to Dual DIP8 Adapter + 2x SPARKOS LABS SS2590 Single Discrete OPA (Unit) in the Aune X8 XVIII and it will improve the audio quality compared to the existing SS306?
Note that the Aune X8 doesn't come with an SS3602 installed.
Maybe it's obvious but it's better to remark it to avoid funny surprises and wrong expectations
If you notice an improvement, or not, in audio quality seems it's a very personal matter.
I didn't notice any change using the SS3602, at all.
The only noticeable thing was a slight increase in background noise using the analyzer.
Nothing audible luckily but still a bit disappointing.
Very likely the odd position of the op-amp socket had a role; the SS3602 sticks out of the Aune like a giant antenna...