Nuforce step up from Sunfire for B&W 803N?

The Sunfire can put out a little more RMS power than the NuForce at 4 ohms, but since the Ref9V2SE can pass undistorted 650-watt power peaks the NuForce will actually sound louder when playing music. If you're playing a sustained note the Sunfire might do better, but most of the music I listen to has momentary loud peaks, which again, the NuForce would likely handle better.

As you dip the impedance then the NuForce gets even better as it is able to provide 1300 watts of short term power at 2 ohms and can even handle loads below 1 ohm. The bottom line is that when playing real-world music the Sunfire has no real advantage. Realistically, either amp will provide enough power for the 803N speakers but I have a feeling the Nuforce amps will sound better.

Also, the NuForce 9V2SE sounds great with a good tube preamplifier and that is how I'm using mine.

Thanks for responses so far. As I step up in the world of hi fi, clearly there is no perfect fit. I am very happy with the sound of my setup, but I've caught the bug and am now looking to make it even better if I can within my restrictions of low heat and smaller size amp chassis. I am trying to figure out what I would like to improve in the SQ, and one thing is the visceral impact of bass (organ, kettle drum, etc) and the sharpness of the "thwack". Hence my concern over power, although I've heard that the nuforce has great damping which also contributes to tight bass and may improve the areas I've mentioned above. I may want to smooth out and separate instruments some overly bright or dense recordings, although I'm splitting hairs here. In fact, this may be more a preamp issue, but I'm thinking the bass is an amp issue, no? Another thought is the Spectron. Still interested in Nuforce vs Sunfire opinions too though.

Tvad, thanks so much for your responses. Not sure what you meant by "The bass impact issue is one that might be affected by the power output specs of the NuForce Ref9V2SE". Did you mean affected positively (more impact) or negatively (less impact). I inferred the latter, but want to be sure. As for in-home, I'm really looking at used purchase. A combo of used nufore and a tube pre like Dodd, Modwright, etc, brings me in at 4.5k or less, which I can live with. Actually, would never buy amp new in this mkt, as depreciation is so favorable to used buyer. Now, if I go with the Spectron, that kills my budget for a good preamp. Of course, maybe I should get preamp first as that may have bigger overall impact, but I'm still sorting all this out. Right now, trying to clarify what the nuforce might bring to the table vs the sunfire, and/or if their are other options. (Wish I had room, money and house current to get a Plinius Odean or Simaudio Titan!!!).