Here is what my smartlist looks like now:
[Media Type]=[Audio] [Genre]=[Electronic],[Jazz & Funk],[JPop],[Pop],[Pop//Funk],[R&B],[Rhythmic Soul],[Urban Crossover] [Last Played]=>60d ~sort=[Bitrate]-d ~nodup=[Artist],[Name] ~sort=Random
So this is dependent on tags to eliminate duplicate files. One set of files where this will not work is the following example:
Digital Audio\Prince\1993, The Hits\08-Let's Go Crazy.ape
Digital Audio\Prince And The Revolution\1984, Purple Rain (192kHz)\01-Let's Go Crazy.flac
Digital Audio\Prince And The Revolution\1984, Purple Rain\01-Let's Go Crazy.ape
I added artist into the nodup setting, because there are many artists in my collection with the same song title (especially in jazz where everyone and their mother plays standards).
This may not work out as good as stacking.