In this paper, we demonstrate non-destructive cryogenic probing of monolithic microwave integrated circuit (MMIC) amplifiers at W-band and discuss the implications for the development of large-format focal plane arrays for radio astronomy. Using a purpose-built cryogenic probe station to measure S-parameters and noise temperature of MMIC low-noise amplifiers (LNAs), an order of magnitude increase in efficiency can be achieved when compared with measurements on individually packaged amplifiers. The amplifiers are tested non-destructively, which enables selection based on cryogenic noise and gain; this is crucial for the development of highly-integrated miniaturized receivers for focal plane arrays, such as those used for the measurement of the cosmic microwave background (CMB) polarization and future arrays aimed at probing the epoch of reionization (EoR).