I have only heard ICEpower amps and I have to say that I was impressed. I am a class A, tube amp kinda guy, and I honestly didn't expect to like the sound at all. I was expecting a colder, sterile, flat, dimensionless sound, but after hearing the ICEpower amps (Red Dragon Audio monos), I want a pair. I heard the 100 watt and the 500 watt versions and I was very impressed with both. I wouldn't mind hearing the NuForce amps as well, but I doubt anyone in the Utah area has a pair.