Reb -- I could only find an internal impedance spec for the .3mV version of the Ruby 2. It is 45 ohms (the .34mV might be a little higher.) Its loading range is spec'd at >400 ohms, and our "formula" (25 x internal impedance) predicts an optimum load at 1125 ohms, with a high-optimum of 50% more, which would equal 1700 ohms.
So you can see that, unless you did an A-B and listened carefully, you might not hear that much difference between 1700 ohms and 22k ohms. But make no mistake, there is a difference! I'm not that familiar with Benz, but if they have a rolled-off high end like you say, running them into a higher load might compensate somewhat, but you'd also be "throwing away" some low end output. How much would depend on the cartridge/arm's low end response.
So you can see that, unless you did an A-B and listened carefully, you might not hear that much difference between 1700 ohms and 22k ohms. But make no mistake, there is a difference! I'm not that familiar with Benz, but if they have a rolled-off high end like you say, running them into a higher load might compensate somewhat, but you'd also be "throwing away" some low end output. How much would depend on the cartridge/arm's low end response.