@2channel8 I use 475 ohms because of the cable cap rating and the suggested range by Lyra. Lyra suggests for a 50pF total capacitance loading range should be 510-270 ohms and for 100pF total capacitance range should be 390-200 ohms. My cable is 1.5m and total cap is 60pF, add a small amount for tonearm wiring so I reduced my starting number some. Upon listening sessions anything above 475 ohms seemed too open and bass was restricted, and by open we mean too much high end, not sound stage. Staging actually shrunk some.....
Yesterday I changed my loading to 100K ohms, just to see and listened to about 4 records. It sounded just fine but......I lost resolution and dynamics, as well as sound stage. Any surface noise seemed to be the same. It was like listening with my high cap cable loaded at 121 ohms, so 475 ohms is much closer to being correct from Lyra's mathematical suggestion. This is why my feeling is a phono stage with variable loading is key if you want the best sound possible. I have never tried 1000 ohms, it seems out of the range that Lyra suggests.
@rauliruegas I don't have test bench gear to make any measurements, if that is what you are asking for then I have to bow out, I can't tell you any specific measurements I am getting in my setup when loaded at 121 ohms, 475 ohms or 100K ohms.
JCarr also suggested that can happen if you load the phono stage too low, making the cartridge work harder. It's why he says the use of a lower cap cable allows you to load the phono stage higher resistance values.
If your cantilever does not move freely, I believe it will not ride in the groove easily, it will not read both walls easily and this is when you lose/reduce resolution and also staging draws in.
I only say this because my listening experience tells me this, in my case a 475 ohms loading gives me the highest resolution, dynamics and soundstaging possible as compared to 100-121 ohms and just recently 100K ohms. For my setup, cable, cartridge, tonearm 475 ohms is the optimal setting. Most of this due to how Lyra builds their cartridges, so for me it makes sense. This is why you need to try different settings and listen, but you should understand what is going on at 100 ohms vs 1000 ohms vs 100K ohms.
Cheers