Been following people who have been making electronic music mixes between two cassette decks and a mixer which are worth a listen. The thing that's interesting is that you can pitch up and down in ways that sound nice:

https://www.youtube.com/watch?v=Kzsa1M7s1sk

Anyways, here's the mixes:

Trippy Ambient Cassette-Only Mix by Bop | Rewind Ritual 01

https://www.youtube.com/watch?v=feHvyc69xe4

Cassette-Only Drum & Bass Set by BOP | Live at SK1 Records

https://www.youtube.com/watch?v=CHmBcBPV-3U

DnB mix with cassette tapes (DJ Ponkachonka)

https://www.youtube.com/watch?v=r8jp5TcherI

Cassette mix drum & bass (2005 - 2010) (DJ Ponkachonka)

https://www.youtube.com/watch?v=Cpqui0lo-v4

What's crazy is that at least the portable cassette decks aren't cheap anymore. Look on eBay at prices and be amazed