Dynaudio contour with 30 watt amp

Even if you crank your volume control, your volume level will be still very low. 30w tube amp will quarter the power to your speakers

Technically tube amp won't clip but will simply sacrifice the power. To bring these speakers to 87dB you'll need muchmuch more than 1W.

sensitivity has nothing to do with weather the speaker is tube friendly or not. it's impedance. speakers with relatively stable impedance are tube friendly regardless of db/w/m.
the usable power is what actually defines the ability to drive the speaker.
theoretically you'll only need 2w of power(ha @1khz...), but if the impedance drops bellow 8Ohms the power halfs and even quarters. therefore chances that you'll be missing lots of resolution and you simply waste your money.
i bet it'll be dead silent in the region bellow 55Hz.
i'd use an additional high-pass filter in order to get descent performance above 55Hz where power isn't necessary.

agree there's no damage concern. the volume will be low even if the volume setting will be at maximum.