By coincidence I have owned both a NAP 140 and a MF Electra amp (E100) in the past, though not at the same time!. I assume that the E30 is a pre amp?
You will need an rca to din cable. The Naim was connected to its pre amp (a NAC102 in my case) with a SNAIC 5 pin din to 5 pin din, which also powered the pre. I think an rca to 3 pin din is ok, but worth checking. Try ebay or Naim forums...
Not sure how the MF and Naim combo will sound. You need to check output voltages from the MF and sensitivity of the Naim. Suggest email direct to Naim, who would be more than happy to service your amp, if you so wished.
Great little amp with much greater authority than its 45 wpc (8 ohms) suggests.