The B&C is 7.8Ohm / Eminence is 6.x Ohm. It gives more 0.5dB in aimspice. If there is a problem in the sound output (with it being to high) a 1.0 Ohm resistor in series (1+5.5 Ohm) would be fine (if there is the need). I am not sure the R1 resistor is 5.5 Ohm.