Does noise increase when using connectors with lower pitch?
From comment:


  There are web sites with capacitance calculators. This value is based
  on dimensions. So, you get a figure and cross talk will rise with
  frequency due to the capacitance but the other half if the story is
  amplifier input impedance. Basically the lower the input impedance the
  smaller the effects due to capacitance so maybe do some checks on
  likely values and report back. – Andy aka Oct 7 at 0:07


Paraphrased:


Use online calculator to calculate the inter-lead capacitance
Calculate inter-lead impedance at a frquency of interest
Find out the input impedance of your amplifier
You can now determine amount of capacitive crosstalk using simple resistor divider formula.


My note: the standard way to avoid crosstalk is to ground every second pin ground. This is what's done in high-speed single-ended parallel interfaces such as PATA 80.