Baffled,
You say "I have to believe the difference is subtle. Especially to my untrained ears. . . "
Yes and no. Here is the REAL problem so maybe you can get out of this crazy hobby while you still have any savings: The more you get into this hobby and listen both for enjoyment and critically, it is likely the better trained your ears will get - just like someone who just starts drinking coffee or wine or beer and thinks it all tastes the same at first. However, the more they drink (hopefully not ALL at once), the more refined their sense of taste gets and the easier it becomes to differentiate bewteen the various coffees or wines.
So, right now you may think the differences are subtle, but the better your ears get, the easier you will be able to discern and appreciate the differences (then you will be poor).
So get out while you can!!!!!!!!!!!!!!!!!!!!!!
Trust me, the DON'T want to end up wacked out like me!!