Beginner DIY NAS for music playback (probably Roon) and some photo/video storage

New to the NAS world, but not new to messing with computers.

My desire is to have a NAS that’s between 4-16TB in size, including backup/clone drives. I only have about 500GB of music, but it’s constantly growing and I feel it’s time to take the jump into this.

My interest in NAS’ are for their use as huge storage systems as well as the ability to stream content from them.

For streaming music, I like the sound of using Roon for this. I probably wouldn’t use the NAS much for watching video content, but this may be something I would be interested in doing further down the line.

I do also have a growing family photo collection that I’d store on the NAS. Growing from 0GB, as I’ve only just begun the mountainous task of digitizing old prints we had in the loft.

Really, my priority is having a setup that a) has sufficient storage and backup storage and b) performs well enough that I could stream my music library very quickly, with WiFi or data speeds being the only discernable bottleneck.

I’m not really sure which component/s in a NAS setup would be the most important for this use-case (e.g. CPU, RAM, SSD etc).

Ideally I’d like to spend under £300 for the whole setup, but can go over this if needed. If I need to start with a smaller amount of storage (e.g. 2TB storage and 2TB clone/backup) in order to meet my performance requirements (i.e. a more powerful CPU/RAM if needed), I am fine with this.

Suggestions on builds would be massively appreciated! And if you aren’t able to/don’t have the time to suggest a full parts list, guidance on how to shop for different components, and which components I should prioritise, would be awesome.