All the NuForce amps currently available have chokes on the output wiring to supress FM interference. That said, it is possible that if the amps are located very close to the tuner it might still nock out a few weak stations. Stations with moderate to good signal strength should be unaffected.
Other class-D amps do not sample at the ultra-high frequencies that the NuForce does, and so would be less likely to cause this problem. Of course many other class-D amps do not sound nearly as good as the NuForce, but heck, choosing a poorer performing, less musical class-D amp may be an acceptable tradeoff to be able to pull in a couple of weak stations that you can barely get anyway...
Other class-D amps do not sample at the ultra-high frequencies that the NuForce does, and so would be less likely to cause this problem. Of course many other class-D amps do not sound nearly as good as the NuForce, but heck, choosing a poorer performing, less musical class-D amp may be an acceptable tradeoff to be able to pull in a couple of weak stations that you can barely get anyway...