Power supply +/-15V for OpAmp

[MilanAudio]

So, it is little bit improved again based on recommendations here 🙂

 

[WWWWW11]

I do that too - in little bit better way, but inside of device cases 😉

Did you use VITROPERM 500F?
VITROPERM 500F is differ from ferrite.
I don't know what explicitly audible EMI core.

He compared difference of noise of 7805 (in Japanese).
http://www.easyaudiokit.com/bekkan2020/TeraTime-4/regulator.html
(Google translated)
Google Translate

Noise characteristic is often omitted by a datasheet.

 

[synonymous]

There's an image in this post that can give you an idea how to use a zener in your project. The voltages at the ldo output down to +-5v. You can of course make some modifications to better suit your needs.
Scheme for regulating power amp rails down for IC's

 

[MilanAudio]

There's an image in this post that can give you an idea how to use a zener in your project. The voltages at the ldo output down to +-5v. You can of course make some modifications to better suit your needs.
Scheme for regulating power amp rails down for IC's

Very interesting! It could be my next project.