  Most microwave readout architectures in quantum computing or sensing rely on
a semiconductor amplifier at 4 K, typically a high-electron mobility transistor
(HEMT). Despite its remarkable noise performance, a conventional HEMT
dissipates several milliwatts of power, posing a practical challenge to scale
up the number of qubits or sensors addressed in these architectures. As an
alternative, we present an amplification chain consisting of a
kinetic-inductance traveling-wave parametric amplifier (KI-TWPA) placed at 4 K,
followed by a HEMT placed at 70 K, and demonstrate a chain-added noise
$T_\Sigma = 6.3\pm0.5$ K between 3.5 and 5.5 GHz. While, in principle, any
parametric amplifier can be quantum limited even at 4 K, in practice we find
the KI-TWPA's performance limited by the temperature of its inputs, and by an
excess of noise $T_\mathrm{ex} = 1.9$ K. The dissipation of the KI-TWPA's rf
pump constitutes the main power load at 4 K and is about one percent that of a
HEMT. These combined noise and power dissipation values pave the way for the
KI-TWPA's use as a replacement for semiconductor amplifiers.
