I can't speak to the Nuforce, but do I own an earlier version of the Concerto (the Concentra), and it is far and away the best SS integrated amp I have owned. Obviously system synergy is a very big factor, so you might get some better answers if you listed your associated equipment. With my Concentra, I am using Green Mountain Audio Callisto speakers, an Audio Aero Prima CD player and an Audio research CD3, and a vintage Accuphase tuner. I also run my (two channel) home theater through the amp.
Aside from sound quality, the Rowland is the single best made component I have owned. The quality of construction and attention to detail are both remarkable. It's also worth considering that the sound can be taken to another level by running a truly balanced source into the balanced XLR's in the Rowland.
Hope this helps a bit.
Tony