“the cronus magnum iii has a built in MM/MC phonostage, woudl it be overkill? and do i pair the phono to the rogue audio, or to the EAT turntable, or can I go with another brand”
Are you asking whether the cartridges you’re considering might be overkill for the Cronus’ internal phono? There’s no simple yes-or-no answer — the built-in stage can be surprisingly good for the money, but depending on the cartridge, it could also become the bottleneck in your system.
As far installation, the outboard phono stage connects between your turntable and the integrated. In this setup, you’d be bypassing the internal phono section of the Cronus, so all of the amplification and EQ duties will be handled by the dedicated external phono stage.
My recommendation, speak to Rogue Audio about auditioning their Ares II or Ares II Magnum. Synergy and improvement in sound (if any) should be much easier to realize with Ares than driving yourself crazy with plethora of options available in phono preamps.
In the end, it really comes down to how much effort you’re willing to put into auditioning phono stages, and ultimately finding the one that feels truly worthwhile — both in terms of the improvements it brings and the money spent.