[Eeglablist] re-referencing with 8 electrodes

[Julia Schumacher]

Dear EEG experts,

We have recorded resting state EEG data using the Neuroelectrics StarStim system from only 8 electrodes (P7, PO7, O1, Oz, O2, PO8, P8, F3). During recording an earclip was used to connect a dual reference electrode (CMS and DRL) to the left earlobe. 
I am now wondering if it is necessary (and useful) to re-reference the data during preprocessing? And if yes, is there any recommended way to do this with such few electrodes? If I understand it correctly, average referencing would not be valid in this case?

Some subjects also show quite a lot of 50Hz line noise. I have tried using the cleanLine function (after applying a bandpass-filter between 1 and 80 Hz) which does reduce the line noise a bit, but it is still quite prominent. I have also tried using a notch filter (EEG = pop_eegfiltnew(EEG, 49, 51, [], 1, [], 0)) which doesn't help much either. Is there anything else I could try in this case?

Many thanks in advance!
Best wishes,
Julia