But.... I can't listen to it?

What isn't working? Does the player show up for you? Mabye try reloading the page. Player embeds can be a bit flaky. Or if that fails, go straight to mixcloud: mixcloud.com/groschi

This is all I saw. Maybe it's firefox.

It works for me. It could be an adblocking issue. If you use an adblocker, try whitelisting mixcloud.com or just deactivate it for the moment (don't worry, no scary stuff on my site).

Yeah, that's most likely the issue here. I just noticed that ublock origin blocks mixcloud embeds for me too. Just deactivate ublock or whatever adblocker you use
for the domain onetwoxu.de, it should work then.

You actually make the tapes and transfer them? Or maybe these are old tapes?

I do the mixes straight to tape using a laptop running @mixxx and an ancient Vestax VCI-300 DJ controller. Then i digitize the cassettes and upload them.