Have you heard those speakers (NHT 2.9) with any other amplification or receiver? I'm still digging a little, but it would appear they need a little special attention in placement. NHT recommends the rear of the cabinets to be 4" to 10" off the wall.
Here's a review I found on them for an impression.
*Edit: Found some specs.
Description: Four-way, floorstanding, acoustic-suspension loudspeaker. Drive-units: 1" fluid-cooled aluminum-dome tweeter, 4" polypropylene-cone upper-midrange unit, 6.5" polypropylene-cone lower-midrange unit; 10" long-throw polypropylene-cone woofer.
Crossover frequencies: 100Hz, 320Hz, 3.5kHz.
Frequency response: 26Hz-26kHz, ±3dB. Sensitivity: 87dB/W/m. Impedance: 6 ohms nominal, 3.1 ohms minimum. Recommended amplifier power: 30-250Wpc.
Dimensions: 39.5" H by 7" W by 21.5" D. Weight: 78 lbs.
Finishes: gloss black; mahogany or sycamore, add $175/pair.
If those specs are accurate your receiver shouldn't have too much trouble driving them to more than sufficient levels (depending on how far you sit from them). However, read that review I linked. Placement with those speakers seems pretty critical. They recommend closer to a wall than most speakers.