It really depends on the tablet, somehow it should sense it's own charger and try to draw the 2.5 amps. If you connect it to something else and it uses a standard usb connector, it should either only attempt to draw the usb standard 500mA or somehow it will also sense the 1A capacity of the speaker dock and draw that. If the tablet is poorly designed, it will just try to draw 2.5A all the time, at which point you'll run into problems. The tablet should come with a warning not to use other chargers in that case. Also, it could give a warning of unauthorized charger from the device.
If the speaker dock isn't designed to protect itself from overload, it will quickly overheat and fry from the extra draw. Hopefully it would have some sort of over current protection(OCP).
i5 2500k P8P67 PRO 16GB Corsair XMS 1600 Intel X25-M 80GB G2 XFX 5850