Matching cartridge to phono pre amp. pF!?

pF = picofarad, one-trillionth of a farad, the unit of capacitance. “Pico” = 10 to the minus 12 power.

Only 100pF. The 2m Bronze MM specs says it prefers 150-300pF.

You can increase pF it with phono cable length. Look at the phono cable specs. 

To the OP:  Are you saying that the specs for the Lehmann say it has 100pF of capacitance at its inputs?  If so, you need also to add in the capacitance of your phono cables.  Any phono cable is likely to have an intrinsic capacitance of at least 50pF, assuming a 3-foot length.  Upper end would be 150-200pF, so if you add 100pF to the cable ranging from 50-200pF, you are in the right ballpark for total capacitance.  How important is this?  It's nice to stay within the manufacturer's recommendations for the cartridge, but rules are plastic in this hobby.

I suspect that there are NO perfect audio systems in the world. At least, not high end. Why? Because matching every spec for all the equipment  is far too rigorous and maybe expensive. Then too, IF you had the perfect system, would it sound any better to a majority than those imperfect ones? I have little or no electronic experience other than user  operation. But I know that perfection is rarely if ever achieved in this fallen world. Just my $0.02 worth

Don't worry about it.  In almost all cases, the cables between the phono stage and the cartridge will have adequate loading.  And it's NOT important.

Sent this same question to Ortofon last year; here’s their reply:
"The parallel capacitance should be in the range of 150-300pF. The higher the capacitance value of the input of the phono stage, the duller the sound will be. The lower the capacitance the brighter the sound gets. A mismatch results in either a dark dull sound or an over bright distorted signal. The capacitance of the phono cable should be taken into account when matching the cartridge to the phono stage as the capacitance of the cable adds to the capacitance of the phono input."

Since I can adjust pF value on my McIntosh MA352, I just set the value to 100pF per recommendation of McIntosh. I’ve tried 50pF and 150pF and 200pF but 100 pF seems to be the sweet spot for the Ortofon 2M Black.

McIntosh recommended 100pF knowing what interconnects and cartridge you are using? Or what? Because the best choice, if capacitance loading at the input is selectable, would depend upon those two variables.

In short yes, because I told their support line what I was using and what Ortofon recommended. The exact advise was to "start at 100pF" and adjust to hearing / taste.

There's not much data on pF for most interconnects. I did find the interconnect from Pro-Ject listed 100pF in their specifications but to previous points also need to factor in tonearm.

My point is 100 pF is a starting point and trial and error from there. On the MA252 the pF setting is locked in at 50pF.

Lewm and bpoletti have it exactly right. Capacitive loading is the sum of the capacitances of the tonearm’s internal wiring, the output cable, and the phono stage input capacitance. If Lehmann BC has 100 pF and your table has 150, not an unlikely value, you are close enough to Ortofon’s spec not to be concerned. A DIY perfectionist would add a small poly film cap across the RCA input jacks inside the phono pre. DB Systems sold a kit with Y connectors and loading plugs that achieve the same result without soldering or voiding the warranty. 

Moving coil cartridges are immune to capacitance loading. A factor in their superiority over moving magnet cartridges. The Grado moving iron cartridges are also not affected by capacitance. They have low inductance coils. The SoundSmith cartridges (derived from Bang & Olufsen) also are low inductance (moving iron, like Grado).

The more inductance/capacitance the slower the transient speed of a phono cartridge.