Impedance Loading for SS Hyperion

"470 - 1000Ω" says Peter Ledermann. My phono stage offers 400. 800, 1,200. so I used 400 initially (extremely smooth), decided 800 was better (some edge present) and 1.2k even better still. There is one higher setting allowed for the MC input (along with several lower ones), 47k. So I’m trying it, and I like it. I keep swapping to the London Reference I am comparing the Hyperion to, and it seems the higher the impedance loading, the closer they sound. I am not experiencing the "peaked high end" I was warned of if loading is increased over 1000Ω.

Maybe my half a remaining ear (thanks, streptomycin!) simply can’t hear the cartridge screeching. Might work for others with high frequency loss? I think the issue is that I have a powered sub that is making sure I hear some bass whatever the loading is set to. If I turn it off the Quad 2905 speakers alone don't sound as if I'm listening to the full range of sound. Perhaps I should set the loading without the sub, and then do my usual procedure of setting the sub volume so I cannot tell that it is switched on, but all the same things sound better?