Your speakers are nominally 6 Ohms and we would have to see what their impedance trace looks like over the listening bandwidth. Part of that bandwidth may be substantially higher than 6 ohms for a small portion of the response while there may a deep dip to a lower impedance across a critical portion of the curve, for instance in the mid or lower bass, and, if bass or warmth is important to you, then the 4 Ohm taps might work better.
This is why it is so important to try all options and choose that which works for your ears. You will do no harm.
This is why it is so important to try all options and choose that which works for your ears. You will do no harm.