  We show that exact loss compensation can be achieved in active metamaterials
containing spasers pumped over a wide range of pumping values both below and
above the spasing threshold. We demonstrate that the difference between spaser
operation below and above spasing threshold vanishes, when the spaser is
synchronized by an external field. As the spasing threshold loses its
significance, a new pumping threshold, the threshold of loss compensation,
arises. Below this threshold, which is smaller than the spasing threshold,
compensation is impossible at any frequency of the external field.
