As an addendum to my previous post, in this Soundstage Review of the Nova there is a quote from David Solomon in which he states, "the Nova will be stable down to 4 ohms, as long as the speakers impedance doesnt drop below that. If your speakers tend to drop below 4 ohms, he recommends you use an external power amplifier."
Based on this, I would not recommend the 4 ohm/87dB speaker since it's almost certain the impedance of this speaker drops below 4 ohms.
Based on this, I would not recommend the 4 ohm/87dB speaker since it's almost certain the impedance of this speaker drops below 4 ohms.