Just for fun I substituted the MCM 53-480 shielded titanium dome for the Fountek ribbon (a $14 metal dome tweeter versus an $88 ribbon). The 53-480 appears to be the shielded version of the tweeter used in the Bottlehead Straight 8. The Fountek offers considerably more detail combined with a more relaxed sound. The MCM sounds more forward, which would appeal to many who listen to popular music. It's not my cup of tea, but overall I'm surprised how much better it sounds than I had expected. This would be a reasonable "starter" tweeter for someone building the FredArrays on a tight budget, and they could upgrade to the Fountek later. However, the Fountek would require a different crossover and some baffle surgery; it isn't a drop in replacement. Now, I wonder how that Vifa DX-25 would sound?