  Due to the pervasive nature of decoherence, protection of quantum information
during transmission is of critical importance for any quantum network. A linear
amplifier that can enhance quantum signals stronger than their associated noise
while preserving quantum coherence is therefore of great use. This seemingly
unphysical amplifier property is achievable for a class of probabilistic
amplifiers that does not work deterministically. Here we present a linear
amplification scheme that realises this property for coherent states by
combining a heralded measurement-based noiseless linear amplifier and a
deterministic linear amplifier. The concatenation of two amplifiers introduces
the flexibility that allows one to tune between the regimes of high-gain or
high noise-reduction, and control the trade-off of these performances against a
finite heralding probability. We demonstrate an amplification signal transfer
coefficient of $\mathcal{T}_s > 1$ with no statistical distortion of the output
state. By partially relaxing the demand of output Gaussianity, we can obtain
further improvement to achieve a $\mathcal{T}_s = 2.55 \pm 0.08$. Our
amplification scheme only relies on linear optics and post-selection algorithm.
We discuss the potential of using this amplifier as a building block in
extending the distance of quantum communication.
