Ok, first some terminology:
In MC the "Library" refers to the database files that MC uses to store information about the media files, settings, etc. A lot of people call their media files (songs, videos, etc) their library. But in MC Library means just the database files.
As such, MC's library really should be stored on an internal hard drive. It's rather small; just a few megabytes (not gigs, megs). So it's no problem. So you can create a new library in any empty directory on your internal drive and MC will populate it with it's database files, giving you an empty database. Then you could import, just like you did in your first library. This does NOT move the media files. It just makes references to them in the database (library).
But there's really no reason to do that in your case. You just want to separate out your audiophile quality songs from your regular ones right? You can easily do that in MC with a view instead. You can have the default view, which shows everything. Then a second view that shows just the audiophile stuff. A third view can show just the non-audiophile stuff. You can switch views just by clicking on them. Switching libraries takes more time (20 seconds or so). Libraries can't ever be combined. Views really are the best solution in most cases.
Let's make it easy for you to start. Do this:
Go to one of the views (on the left) that you like. Let's duplicate it. Drag that view up to the upper level where it says "Audio". It will ask if you want to move or copy. Choose copy. Now you'll have another copy of that view with a (1) after it.
Let's alter it to *only* see your audiophile files. Right click on it and choose customize view. Now Settings > Included Files > Set rules for fie display . In the search wizard that comes up, choose:
Filename Starts With (type in your drive letter and path here) .
Click OK several times. It may ask you if you want to overwrite the view; say yes if it does.
Now this view should only show you the files from the audiophile drive. Right click the view and change it's name to something that makes sense like "Albums (audiophile)". Repeat this entire process and create a new view that shows only your non-audiophile files.
Now you can see everything in the stock views. You can see the audiophile stuff in one view. You can see the non-audiophile in another view. You could take this further and create new top level items like Audio (audiophile) and have multiple views below that for Album, Artist, etc. This probably isn't necessary, but it's not hard to do. Views inherit the rules from their top levels, so you can add your file selection criteria once and then every view below that will have that same criteria.
I hope this all makes sense. Ask questions if you need help. Good luck!
Brian.