I have been thinking of picking one of these up for comparing various amps with various speakers. Any of you own one? Are there any downsides to using a Z-Matcher? I'm guessing that it is just a big o' transformer with switches for primary and secondary windings. I'm also wondering if using a Weber Mass attenuator (impedance swamping) on one of the parallel outputs for balancing speaker volumes might have any ill effects other than the usua tonal side effects of attenuators. I should probaby just hit up Weber with this question.