Tested with Altec speakers, of course! (and others) Tube amps, solid state, Class-D. From a living room in Hawaii to a bedroom in Oregon to a dedicated listening room in Carolina to show spaces in Washington D.C.
Have also used them as coupling caps and been very happy with them. They are by far the best value for money film cap I've found. I also like the Obbligato caps, but they are large and somewhat expensive. They come from Hong Kong. There are others, but I just always some back to the Janztens.