Not when you stop to think about it. Additive power implies that an angreal was built to add 100 units of OP to a channeler, which implies that there is a cap so that it is only ever able to add 100 units of OP. The buffer on this device would also protect a channeler from the damage the additional 100 units of OP would do to them. So, Lanfear would thus be able to use this device to channel 200 units of saidar with no damage done to her. Lacking a buffer would only mean she could still draw beyond her natural potential (let's say 20 additional units) and thus would burn out. There is nothing in an additive model that suggests an angreal is capable of suddenly increasing it's additive power. A glass only holds so much water no matter what you do.

A magnifier would essentially be both a buffer and an amplifier though. Essentially a 2x magnifier would let Lanfear become a 200 unit channeler as long as the buffer remained in tact, but if there was no buffer the magnification to 2.5x would make her a 250 unit channeler and burn her out and in theory could become a 5x magnifier or a 20x magnifier depending on the individual overdrawing.