I have the 2SE and used the high gain when I had the Etna. It also depends on how loud you listen to your music. The load setting you'll have to test by ear - start w 100 ohms.
Settings for Lyra Etna Cartridge
I currently have a VPI Titan Turntable w a Fatboy tonearm, Lyra ETNA cartridge, Audio Research Ref 10 Phono Stage and Audio Research Ref 10 Line Stage, Transparrent Reference XL cables. Any thoughts on low vs high gain on the AR Ref 10 Phono, Recommended load into MC phono input?