For what it's worth here are my observations. I am running a Koetsu Onyx Platinum (.2mv, 5ohms) into a BAT VKP10 phono stage into a BAT VK5i into VK60 monoblocks biamped with Llano Trinities. The P10 has gain settings of 50 and 55 db in its direct all tube mode (6 6922 for gain) and gains of 67 and 73db if you switch in the stepup transformer. Loading of 100, 1000, 10,000 and 47,000 is builtin. To me the Koetsu sounds best at 55db all tube loaded at 47k. I believe there is some ringing at the higher frequencies which can be cured by going to 10k but with the loss of some dynamics. Going under 10k turns everything to mud and syrup. The volume at the preamp is generally at 50 I(unity is 62) so there seems to be sufficient gain and no loss of dynamics. The bass is satisfactory but see below. My guess is that the best loading would be around 25k. When I switch in the steup (sounds best at 73db) the sound to me takes on the characteristics of a CD: fast, dynamic, and a bass with terrific extension and control; however I lose all the midrange delicacy and air and timbre and so I go back to the all tube mode. This is loaded at 100 ohms and the sound would probably improve by going even lower. At 47k it is unlistenable. However the volume setting on the P10 is now around 30 which probably is not a good thing--losing music to the resistor. So all this means to me is that loading is very dependent on whether or not you are going into a stepup or all tube. I noticed that the Rowland phono stage only offers loading of 200 and 400 and I believe this is true of other solid states and hyrids. Now if I could only incorporate the stepup bass with the all tube mids and highs....
