Hi 2x6spds and Stereohead,
Tube amps tend to clip (go into distortion) fairly gracefully and gradually, generating a big wash of harmonic distortion--3,4,5, maybe 10% or more--which to the ear, doesn't sound unmusical until it becomes really gross (above 10%).
Transistor amps, when they reach output limits, clip suddenly, with unpleasant IM distortion and spurious garbage that can fry a tweeter or woofer voice coil in an instant.
If you pushed a little tube amp too far, it too could damage a speaker through clipping, but audible distortion would typically signal the onset of clipping before damage occurred.
Put your M3ti's close together and use a pink noise signal from a test CD if you have one, or the noise from an FM tuner when the muting is turned off. Set the volume to a moderate level and listen to the nature of the hiss. The two speakers should sound essentially identical. You can put your ear near each tweeter to check that each one is working; do the same for each woofer.
Axiom Resident Expert