Did you google search that reference?
Don't remember reading that term at HF until recently. I am trying to figure out whether that's the same meaning as more revealing and/or more resolving the terms used by some audiophiles. If you mean more transparent sounding, then we are on the same page. :)
I did but I've also been a member on AudioAsylum since 2000 (but under a different moniker ;-)); and remembered the term from there but I did need to search which post had it. I haven't bothered to check whether "micro detail" was defined in HF's Glossary of Terms (checking, seems not).
Hmmm, personally in my definition of micro detail it's not about transparency. To me it's probably more related to the "resolving" term you mentioned above.