Secondly, most good preamps will pass DC which will of course create havoc with your woofers.This statement is entirely false. No preamp made passes DC!
Regarding loading:
If loading is affecting the sound, it suggests that the phono section is unstable with RFI at its input. Once corrected you will find that the loading no longer is needed.
The loading is used to detune a high frequency resonance caused be the inductance of the cartridge and the capacitance of the tone arm cable (inductance and capacitance are the building blocks of Radio Frequency circuits). This resonance is usually well above the audio band and can occur at several MHz.
Many circuits don't sound right in the presence of RF energy so eliminating it or the sensitivity to it (which yields greater benefit) is quite audible.
I discussed this issue with Jonathan Carr of Lyra fame a couple of years ago at Munich. We both had come to the realization that low impedance loading of a cartridge is probably adversely affecting its compliance, and so it likely reducing its performance in some tone arms. The idea is damping, not unlike how an amplifier can damp a loudspeaker.
So if you chose a cartridge to work in an arm based on its compliance (and resulting mechanical resonance), loading the cartridge may throw things off a bit.