Estelon claims 87 dB sensitivity for the XB but our pink noise figure of 84.1 dB indicates that this is optimistic. So too is the 6ohm nominal impedance, which suggests a minimum modulus of 4.4ohm. Estelon claims a 3.5ohm minimum but we recorded a dip to 2.9ohm. Impedance phase angles are quite high, so the EPDR (equivalent peak dissipation resistance) falls to a low figure, the minimum of 1.4ohm at 60Hz suggesting that the XB is quite a difficult load to drive. The on-axis frequency response [Graph 1, below] shows a declining trend above 8kHz despite which, because of the smoothness of the traces, any errors were limited to a mere ±2.4 dB and ±2.1 dB respectively - excellent figures.
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