The following link is a great source of info about RIAA designs. A great collection of schematic topologies and measurements. A must read material. The site includes variety of industrial schematics. Some of them are pretty old but could be easily adapted and brought back to date using the modern component base.

Now this one is a real gem:

It’s a design by Linsley-Hood. This one could be easily optimized for even lower noise. What comes to mind is the Toshiba’s 2SK170 JFET. This will drop the input bias circuit and the need of input capacitor. Plus – more JFET’s can be paralleled to reduce the noise floor even further at no real penalty. The only problem is the hfe matching between the JFET’s.

Be sure to read the article here – >>>  LINK  <<<