Van1,
The Quantums in question here are not HF noise filters. They are designed to be used with or without noise filtering PLCs, or any type for that matter.
You are right about many high-end components not needing additional filtering.
However, there are other types of PLCs that address power factor correction, quantum noise, and electronic artifacts, not normally addressed by conventional filters or transformers.
I own some earlier, less expensive Quantum products, and they give a small improvement when placed in certain areas of the system. The Qx2 and 4, I have heard at a show, no A-B demo was done, so I can't say how effective.
The Quantums in question here are not HF noise filters. They are designed to be used with or without noise filtering PLCs, or any type for that matter.
You are right about many high-end components not needing additional filtering.
However, there are other types of PLCs that address power factor correction, quantum noise, and electronic artifacts, not normally addressed by conventional filters or transformers.
I own some earlier, less expensive Quantum products, and they give a small improvement when placed in certain areas of the system. The Qx2 and 4, I have heard at a show, no A-B demo was done, so I can't say how effective.