Power amplifiers stereo — PrimaLuna EVO 400-4

The EVO 400-4 is a stereo power amplifier from PrimaLuna, part of the brand's EVO line of tube electronics built around flexible operating-mode switching between Class AB triode, ultralinear and pentode configurations. This power-only design pairs naturally with a separate EVO preamplifier, giving a listener full control over tonal character and dynamic drive independent of source or volume-control electronics.

Key specs that matter

Output power varies meaningfully by operating mode into 8 ohms - 70W in one setting, rising through 72W and 85W to 89W in the most powerful configuration, with ultralinear mode delivering a consistent 30dB of gain across all four power settings and triode/pentode modes ranging between 26-27dB. Input sensitivity is 1,100mV, with input impedance held at a substantial 100k ohms whether the connection is balanced or single-ended, easing gain-staging with virtually any preamplifier. Frequency response extends from 8Hz to 70,000Hz within plus-or-minus 3dB, a wide window for a tube design. Signal-to-noise ratio spans 95-105dB depending on operating mode, with total harmonic distortion plus noise held under 0.1% with full global feedback engaged. Maximum power consumption is 550W. At 405 x 385 x 205mm and 31kg, substantial weight reflects serious output transformers and power-supply componentry rather than cosmetic bulk.

Sound and use context

Expect the operating-mode flexibility to reshape the amplifier's character to taste - triode mode typically favours a more delicate, harmonically rich presentation at lower power, while ultralinear and pentode modes trade some of that intimacy for greater output and control, letting a single amplifier adapt to different loudspeakers or listening moods without needing separate hardware.

Pairing

The wide 100k ohm input impedance and generous 1,100mV sensitivity make gain-staging with almost any preamplifier straightforward, and the substantial power reserve across all four operating-mode settings suits loudspeakers spanning a considerable range of sensitivity and impedance.

Alternatives

PrimaLuna's own EVO 300-3 and EVO 400-3 preamplifiers form the natural upstream partners for this power amplifier within the same EVO family, worth pairing together for a coherently voiced, fully tube-based signal chain from source through to loudspeaker. The consistent 30dB ultralinear gain across every power setting means switching modes never requires a corresponding volume adjustment at the preamplifier.