Gliderguider: I agree with what you said about ultrasonics, but i wanted to be honest and fair as to the pro's and con's. Like you, i've never heard of anyone popping an amp or tweeter that was directly related to this phenomena. As a side note though, Philips evidently thought that this was serious enough to allow one to select the hinge frequency for filtering on their SACD 1000's. They specifically mentioned "potential for damage to amps and tweeters" when selecting the 50 KHz ( maybe it was 40 KHz??? ) filter. I ran mine at the highest setting with speakers that were flat out to 23 KHz and an amp that was linear out to 80 KHz and capable of over a kilowatt of output per channel with nary a problem for about a year. Sean
>
>