Now looks like the switchover to remix.audio has been fairly seamless, with even the embeds working fine. But I think the sowndhaus.audio domain will not be renewed, so the redirects will stop working. So make that change now!

Some advice for changing your URLs for Wordpress users, it can be a bit daunting but just done it in 5 minutes for Radio Clash and my Mutantpop mashup blog. I really recommend a plugin called Better Search & Replace https://wordpress.org/plugins/better-search-replace/ - that's what I've used and used before.

A few tips:

Backup your database! Either manually via the server or a plugjn like BackWPUp. You could do it via Wordpress's own XML backup Tools > Export but personally I don't truss it to backup EVERYTHING, it will just backup your posts etc, whereas a database search and replace can affect other tables than WP's own.
Search for 'sowndhaus.audio' and replace with 'remix.audio' (without the quotes) and make sure Dry Run is ticked. You can select Case Insensitive if you think you might have say Sowndhaus or SOWNDHAUS in your links or embeds - I did, seems to have run OK).
Look at the log. Keep a eye on it changing weird non-wordpress tables, (ones that don't start with wordpress_ or your blogname_) but should be fine, SEO/broken link managing plugins will also trigger but they need to be changed also.
If all seems fine, run it again without Dry Run checked.

Why 'sowndhaus.audio' not 'sowndhaus'?

Well I am SUPER cautious with stuff like this, and tbh it's better to change all the links and embeds FIRST - to be super sure you could even run 'sowndhaus.audio/embed' > 'remix.audio/embed' and be sure you're just changing the embed links, then search for the links separately - say 'https://sowndhaus.audio' > 'https://remix.audio' - be sure that ALL your links are https:// though and not http:// in places.

But doing the domain URL first, means you can then do the Sowndhaus mentions later, so say you could change those all to Remix or Remix.audio or Remix mashup site or whatever. Personally I'm leaving the old mentions, just changing the links/embeds, but I have that option later if needed.

Hope this helps!