This communication investigates the sensitive behavior of dynamic resonant scattering when an extended system is weakly coupled to a resonator (high-Q) and the source field is nearly monochromatic but of finite energy. We analyze a specific model that incorporates certain universal features of resonance. It is a resonant modification of the Lamb model for the interaction between an oscillator and a continuum. This resonant Lamb model incorporates a two-part scatterer attached to an infinite string with continuous spectrum. The non-resonant part of the scatterer is associated with direct scattering; and the resonant part—an oscillator coupled weakly to the string— is associated with field amplification and delayed scattering. A sharp anomaly in the transmission coefficient occurs when the source frequency is within γ2 of the resonant frequency (where γ is the coupling constant and the Q-factor is of order γ−2); this anomaly is mollified as the source spreads spectrally. Resonant amplification occurs when the source frequency is within γ of the resonant frequency. The amount of amplification depends on the relationships between the spectral width γ2 of the transmission resonance, the spectral width σ of the source field, and the difference between the source frequency and the resonant frequency.