I'm not quite as sensitive as Russtafarian. But most highly resolved solid state amplifiers are fatiguing for me. It isn't by choice, it just happens to be and that's unfortunate.
Unlike Russtafarian, tripath based amplifiers have been OK from the fatigue point of view, but they typically also have rolled off highs and a certain harmonic flatness. NAD makes solid state amps which are not fatiguing, but they're also somewhat murky, congested and thick.
Even the very sweet and slightly warm (but highly resolved) First Watt J2 is somewhat fatiguing for me. On the other hand, there has never been a tube amplifier, no matter how well resolved, which has been a problem for my ears. It's why I've previously gone down the highly efficient speaker path, to have a suitable speaker that is easy to drive from low power tube amplifiers like SETs.
I'm currently using an LFD Zero LE MKIV integrated which is solid state, resolved, but not a trace of harshness, brightness, fatigue or edge. It's a real rarity.
Nuforce gear is very good indeed, and I've previously owned one of their preamps, one of their integrateds, and their HT processor. But the integrated just didn't work very well for me at the time. They're very good but they may not be for everyone. Always good to audition the gear at your dealer and preferably in your home.