newbie question: Accessing music on HD or flash memory on various android devices

[currter]

I had attempted to use Spotify in the past with some Medion wi-fi speakers I have but did not do much with it. Comes now, I have a Fiio device and an LG 8.0 Tablet and I have music in forms of flac files stored on the microSD cards and/or a hard drive attached via USB connection.  I am just having problems trying to access the 19,000 or so flac files I have stored in my personal library (ripped from 1300 CDs I own). Must I upgrade beyond the basic service to be able to access the files I have stored as I am only seeing how to download songs via the internet, which is not what I want to do just yet since I have a massive audio collection.

Thank you.