Depends::
How loud do you intend to play 'em? What is the electrical phase angle and the frequency of the low impendance dip?
Under moderate phase angles and at high frequencies where there is lower musical energy, you should be able to get away with nearly any good amp which will not meltdown into 4 ohms.
If it measures something weird, like 60degrees from 100hz to 600hz with the impedance dip in that range, you'll need some substantial amp to back it up.
disclaimer::
Never heard 'em, but simply speaking from an electrical / engineering view.
How loud do you intend to play 'em? What is the electrical phase angle and the frequency of the low impendance dip?
Under moderate phase angles and at high frequencies where there is lower musical energy, you should be able to get away with nearly any good amp which will not meltdown into 4 ohms.
If it measures something weird, like 60degrees from 100hz to 600hz with the impedance dip in that range, you'll need some substantial amp to back it up.
disclaimer::
Never heard 'em, but simply speaking from an electrical / engineering view.