Nicotine+

fmhy.net for all your sailing needs.

Usenet. Plenty of music in lossless (FLAC) format. Use NZBGeek and DrunkenSlug as indexers. Sabnzbd to download. Lidarr and Prowlarr to automate everything. Add an artist, click to download an album, and it'll search for the album, download the NZB file, send it to Sabnzbd to download, then tag and organize the files once it's done downloading.

For music I'd just get a block account: https://www.reddit.com/r/usenet/wiki/providerdeals/. Essentially, you pay for some amount of data (can usually get 1TB for US$5-15), and they usually don't have an expiry date, so it could last you for years. Some providers have monthly plans with unlimited data, but a block account will end up way cheaper if you just want music.

For rarer music, Soulseek is very good. It's a peer-to-peer service from the KaZaA and Napster era, but somehow it's survived until now. Since it's peer to peer, downloads are quite a bit slower (you're relying on the upload speed of individual users - each download comes from only one user) but it's a great community.

Soulseek and lucida.to are the best of the best

relatively niche old death metal

I have no idea how much it should be "relatively niche" and "old" but here's a few sources i'm using myself for such type of content:

https://metalarea.org/forum/

https://en.metal-tracker.com/

https://deathgrind.club/

https://in-the-fog.ru/

https://vk.com/sbdm_community

Most of them require a sign-up

Fun fact: you can write a Bash script to run yt-dlp on a playlist without much scripting skill

Slskd

It uses the soulseek servers. Can run your own instance in a docker container. I listen to metal daily and you can find anything from other soulseek users.

I've had about half my music on an SD card for the last 10 years but now I've finally canceled my streaming subscriptions and am comitting to having everything on there, are there any good front end apps for that? Rn I use poweramp but it's playlist making options are awful.

Also sorry if this is the wrong place to ask, if so please just point me to the right place

I normally use Deemix-GUI to download from Deezer, or fire up Nicotine.

I use tidal-dl-ng, simple python gui app you can compile yourself or even just run in the debugger.

i think orpheusdl works for deezer/tidal/qobuz. you can also try running your windows-based downloader program under wine, it might actually run really well

https://github.com/NickvisionApps/Parabolic/releases

this is great for downloading from apple music, youtube music, ect