Forgive a bit of time since last working with these cartridges, but I set up several turntables with ADC cartridges back in the mid to late 1970s. They were quite good performers, tracked well, generally had low distortion. If my memory serves if there was a shortfall it was inconsistency in performance occasionally, meaning their QC at the factory was not as high as Shure with their V15 series or Stanton with their 681 series, both excellent. In fact Stanton was easily the industry leader as far as consistent performance from unit to unit went. The guy who frustrated me all to hell was Joe Grado, whose QC as terrible. He could make the best sounding cartridges, but also ones that just wouldn't set up properly at all. And when we would return them as defective he was, well to put it mildly, not well pleased. Anyway, back to ADC, if your cartridges track well, and you can hear if they do with any good test record, use 1.0 gram VTF, then you have good ones. They should sound on the lean side of neutral and track well across any well made record with no distortion.
ADC moving-iron cartridge has "low" output
I have two identical ADC gold-body XLM-III carts from the late 70s. I purch'd them used, as part of two turntables that were each purchased from different parts of the US. Each cart has a different model of stylus (XLM-III and QLN-2) , and styluses can be interchanged.
The MI series from ADC should output 5.5mV, which I have not measured. However, BOTH these carts are challenged wrt output volume. Not only do I have to crank up the vol. more than 1/3 above other carts, but the sonics are a bit "small" and not "full bodied". It might be due to weakening permanent magnetism -- these are both getting close to 50 yrs old .
The perm. magnet in ADC moving iron series is mounted in the removable stylus, just above the stylus/cantilever assemble.
Not sure what else the low volume may be due to??? These are my my only MI carts in my collection. Anyone know more?