One thing I like about Tannoy ST100/200 is eight selectable crossover points and sensitivity settings. In my application this made them a much better match than the Chinese Lucy ribbons. Correct time alignment can be obtained by varying front-to-back positioning on top of the main speaker. I mount them on an elevated platform to decouple from vibrations across the top of the cabinet.
An ST placed in parallel with the main speaker will change the impedance load on the amplifier. This may effect which amp impedance tap sounds best-- assuming that your amp has the flexibility of multiple taps.
Be aware that whatever cross-over point and sensitivity level is selected, there will be downward embellishment all through the treble region. Tannoy uses a third-order crossover. Their manual includes frequency plots.
Bottom line, the ST is a tool I would not want to be without.
