Your not going to get quality sound downloading songs from youtube. Find a music private tracker or purchased used cds very cheaply. At least get 320 mp3s or V0 if you need space.
Hi, I think you can use this website to download mp3 from youtube for free, you can use it to directly convert YouTube videos to MP3 format.
https://listentoyoutube.ch/en/youtube2mp3 to download Videos with One-Click.