The only way you can tell is to take each home, at the same time and do an A/B comparison in your home with your system.
component and music memory is extremely faulty.
I know there are some dealers that will either let you take a unit home for an in-home demo or take your credit card information so that you can take it home.
Also, make sure you are listening at the same DB levels. Many people even audiophiles mistake volume differences with better or worse.
So, for example if I want to think about upgrading an amp or pre-amp, I will "borrow" a new (new or used) device under consideration. Take it home. Listen to my music at the level I like with my original piece. Digital works best for this example. Then, I insert a test CD and play a test tone and measure the sound level with a sound level meter. There are some inexpensive ones out there and also some apps you can download.
I then remove the original piece, insert the new device, changing absolutely nothing else. nothing. Play the test tone again and adjust the listening level to match the original.
Then listen. Now what differences do you hear? That's the ticket.
Most times with high end equipment, it is not jaw dropping differences, but the question is, are the differences enough to "justify" an upgrade?
That is the fun part.
enjoy