Most of the time the only avenue available is A - B testing.

IE. Try existing item, change, try new item. Make decision

This is all I need (I thought)

ChrisB was the first I can remember saying you had to plug in the new item and live with for a while to truly know

Always very useful when @tonyc drops off kit to try as he leaves it with me so I can try out music I know, swap occasionally.
(Except when he's trying new stuff out. I hear it briefly and he wafts it away !)

Having my playlist of albums is very helpful as I am continually hearing the same wonderful albums.
What has amazed me over the last few days is the improvement I hear from the AudioDesk CD Sound Improver Lathe.

Initial testing of the items Tony brought said the AudioDesk made an improvement and was worth having.
What I now hear from well known albums is so much more than I expected.

Recommendation
Longer term testing is the way to go if you and your supplier can organise it