To get a signal to noise ratio of 70+ dB, single channel op amps are the only ones that offer noise levels low enough. Let's redo the layout, since the existing one uses dual channel op amps. Especially since the design with dual op amps has only ~60 dB SNR.

Hmm, running AC power cables over the input screw terminals for a minuscule MC signal? Not so great. Let's make some AC throughput tracks on the PCB.

While on the subject of input screw terminal, why not move it where the RCA connectors are. And why not move the output screw terminal to where the output RCA connectors are at the same time?

Since this is a complete redesign of the PCB, let's make sure the power screw terminal ends up where the power supply is.

This is a much better layout in terms of getting lower noise, better performance, less interference and easier construction.

Any negatives? The board is larger and it uses more components that also cost more. The input impedance settings went from 15 to 4 presets. That's still 400% more than you get from most others.

I still think this would be better, why settle for something that's "okay" just because it costs a handful of dollars less?

The first prototype cards (with the old layout) are expected to arrive in a few days, and they will let me do those first measurements.

Note that this layout is by no means final, it's more a proof of concept that shows it can be done in that restricted space. (Hey, I even got space over! This gave room for the AC power traces.)

UPDATE:

I consider this board to be a release candidate, and have ordered some PCBs for test. All the pictures on the project page, and the picture on this project log have been updated with the latest version.