Getting the file path of a currently playing iTunes track with Applescript
You don't need System Events, iTunes can tell if it's running or not.

Also, set the properties of current track to a variable and then get the info from the variable. The reason for this is you make only one lower level call (properties of current track) and then the assigning of the other variables gets the info from a variable containing all the info, and not making 15 separate lower level calls to get the info,  This should be faster and more efficient code. 

tell application "iTunes"
    if running then
        set state to player state
        if state = playing then
            set trackProperties to (properties of current track)
            set theArtist to artist in trackProperties
            set theTitle to name in trackProperties
            set theAlbum to album in trackProperties
            set theTime to time of trackProperties
            set theGrouping to grouping in trackProperties
            set theGenre to genre in trackProperties
            set theKind to kind in trackProperties
            set theYear to year of trackProperties
            set theComments to comment in trackProperties
            set playCount to played count in trackProperties
            set theTrack to track number in trackProperties
            set numTracks to track count in trackProperties
            set theDisc to disc number in trackProperties
            set numDiscs to disc count in trackProperties
            set bitRate to bit rate in trackProperties
            try
                set thePath to POSIX path of (get location of current track)
            on error
                set thePath to "Not playing from local library."
            end try
        else
            set state to "none"
        end if
    else
        set state to "none"
    end if
end tell