MC cartridge loading: still baffled

The phono preamp. Having adjustable loading is great as you can play around to see what you think sounds best in your system. I would trust Ayre's suggestions on their equipment.
As for anti Skate, never follow the tonearm's instruction. You adjust the anti skate by test record or by the Schroeder method. When you put the stylus down in the run out area between the grooves it should VERY slowly drift toward the spindle. Not using any anti skate is improper and you can see this easily. Defeat your anti skate mechanism. Viewing the cantilever from the front use your lift to lower the stylus into the groove and watch where the cantilever goes. It will deviate towards the outside of the record as the tonearm leans heavily on the inside groove (left Channel.) What you are doing is increasing the tracking force on the left channel and decreasing it on the right. The right channel now starts miss tracking early. You can hear this effect easily with a test record. This also increases wear on both the stylus and the record. When you set the anti skate correctly you will notice when you put the stylus down that it does not deviate at all.  

Jc, if your anti skate is not set correctly the unloaded channel will only miss track at higher groove velocities so at regular velocities things might sound sort of normal. But, there are more than tracking considerations. For the best performance/low distortion the coil (or magnet) should be placed symmetrically in the magnetic gap. With the anti skate set incorrectly the cantilever will drift to one side or the other and this will not be the case. Again, in the run out area, between the grooves the arm should drift VERY slowly towards the spindle. Use whatever weight or setting of your anti skate that accomplishes this. This will assure you of the lowest distortion, best channel separation and best tracking your cartridge can achieve when it hit the cannons in the 1812 Overture. 

Actually Lewm that is Frank Schroeder's method. I prefer to use the HI Fi News test record as it has an excellent anti skate track and both vertical and lateral resonance tracks. But I have noticed repeatedly that once I set up the tonearm with the record the tonearm drifts slowly towards the spindle on a blank record so Frank's method works. 
When using the test record you are using your ears to detect miss tracking.
I can't count the number of screws millercarbon has loose. Setting up a system is simple once you know what you are doing. The vast majority of "tweaking" is mythology. A really good tech can interpret what a client wants to hear into the system's sound. 

raul, I didn't know you knew how to do math:)