Hi Scott,
Interesting finding. One thing that can significantly affect the tonal balance of a moving magnet cartridge in the treble region, and thereby affect soundstaging and perceived dynamics, is the load capacitance that is applied to the cartridge. And I see that the Clearaudio Maestro V2 has a recommended load capacitance of 100 pf, which is too low for many setups to even come close to achieving. (The load capacitance seen by the cartridge is the sum of the input capacitance of the phono stage and the capacitances of the phono cable, tonearm wiring, and connectors).
I couldn’t find an input capacitance spec for your phono stage, or a load capacitance recommendation for the Shelter 201, and of course I don’t know what the capacitance of your phono cable and tonearm wiring would be. But if you want to change to a different moving magnet cartridge, I would suggest avoiding any having a recommended load capacitance of less than around 200 pf, or an even higher number if your phono cable is longer than say 4 or 5 feet.
Also, I doubt that the difference between 3.6 mv and 4.0 mv has any significance, that being a difference of less than 1 db. However there are two different test records/standards upon which cartridge output specs can be based, which I believe can result in the outputs of cartridges having identical output specs often differing by 3 db. Which in terms of mv means that a 3.6 mv cartridge under the standard that produces a higher number would be only 3.6 x 0.707 = 2.5 mv under the other standard. So that conceivably could be a contributing factor.
Good luck. Best regards,
-- Al
