Denon DL-103 Compatibility

To any of the above, try a high quality heavier headshell, like the Ortofon LH9000 or the AV101 Orsonic, and I think you’ll realize an improvement, even though you’re presently satisfied. It’s not only about the resonant frequency equation.

I have the ZU Audio modified DL103 and it sounds fantastic on my Technics SL1200G.  It didn’t sound good on the VPI prime with unipivot 3D arm.  

I have the 103 mounted on a Grace 707 arm. Sounds fine to me! The lighter the arm the higher the resonant frequency of the cartridge suspension/arm mass. The heavier the arm the lower the resonance.

Where did you hear that? The ideal resonance frequency is between 8-12hz. That arm and cartridge is 13hz. That's pretty damn good!