A densifier (10) for simultaneously densifying two cryogenic liquids at different temperatures is provided. The densifier (10) has a thermoacoustic heat engine (20), a resonance tube (18) and a two stage pulse tube refrigerator (40). The thermoacoustic heat engine (20) generates oscillatory acoustical power required to generate net refrigeration power in the two-stage pulse tube refrigerator (40). The first stage (100) densifies a first cryogenic liquid to a first cryogenic temperature, and the second stage (200) densifies a second cryogenic liquid to a second, lower cryogenic temperature. The thermoacoustic heat engine (20) converts thermal energy to the oscillatory acoustical power required to generate net refrigeration in the first (100) and second (200) stages of the pulse tube refrigerator (40). No mechanical energy input is required, and therefore the invented densifier (10) has no moving parts.