Contrary to common practice, LINN advises the LK140 to be used for the treble. Their logic and credo is, do what sounds best.
The LK140 is a better sounding amp, and so they would have it placed where most of the information heard is.
In a further vein, they recommend 2 LK140s over 3 LK85s, aktiv or passive.
140s are slightly better overall sonically, with more ease thanks to their deeper reserves.
Passive the LK85 will deliver roughly 85 watts to the bass as it is, or 66 aktiv- fairly sufficient for Tukans.