Martin Logan woofer amplification

I was discussing a possible trade in for my Martin Logan Montis speakers. The store owner was reticent, stating that the amplifier for the woofer was an OP amp. I was surprised to hear that, since the operating space is so large. I thought it was a Class D switching amp, which should work well in a non ventilated cabinet, and operating at a low frequency. Any Martin Logan experts out there?