I’m not using a SUT, though it’s something I’ll try in the future. I use a Naim MC only Superline upgraded with their supercap power supply. I load the Royal N with 220Ω and the Proteus with 100Ω, The arm is a Schröder Reference. I do have Naim’s rather more primitive stageline N MM phonostage as well but it only has 35dB of gain, I bought it for my mono wired Decca which I use on a Townshend Rock mk2, with which it’s works very well but since the Royal N ideally wants no more than a 20:1 SUT it doesn’t have enough gain for that and I’d need to look elsewhere. I’ll probably need something rather better too. My history with separate phono stages is limited to the Tom Evans built Michell iso (now rather old) and the Superline, both MC only, plus the Stageline N.