All of my larger speakers use compression drivers, and I only use the piezo in speakers that won't be used much above 30v. I really like the little Motorola tweeters, but I find them best suited for smaller systems. But then again, I've run 'em for years on ultra high powered Crown amps, and never smoked one. They should burn out at about 40v, but I've just never smoked one. The woofers in these systems will fail long before the tweeters, and that is probably one reason why I haven't damaged a quartz tweeter. They're just in smaller systems.