Amplifier choices for building a more capable hi-fi system

The Mola Mola Kula is the most complete all-in-one amplifier proposition in this selection.

Its basic form is an integrated amplifier with six switchable analog line inputs, split between three balanced XLR and three unbalanced RCA connections.

The design is modular, allowing the amplifier to be supplemented with a phono stage and a DAC section based on the company’s Tambaqui design. That flexibility is the point of the Kula. It can sit at the center of a system built around analog sources, digital sources, or both, without forcing the buyer into every module at the outset. The source also highlights balanced circuitry, processor control, channel selection, phase inversion, mono summing and a Mastering operating mode. Power is specified by Mola Mola at up to 150 watts per channel into 8 ohms or 300 watts into 4 ohms.

The Noble & Noble Nobilis Sonum 98 is not a conventional standalone amplifier, but it is relevant to amplifier shoppers because amplification is built into the speaker system itself.

The source describes floor-standing acoustics with built-in amplifiers, DSP, three digital inputs and two analog inputs, controlled by a small wireless remote.

Its cabinet concept is the headline feature. The seven-sided enclosure and L-shaped front structure are designed to resist unwanted vibration, while the low-mid-frequency driver arrangement uses two tightly coupled drivers operating in antiphase to neutralize parasitic vibrations. For a buyer considering whether to separate electronics and speakers, this is the integrated active-system alternative in the list.

Klipsch’s Reference Premier subwoofers are included here because each model is an active design with its own Class D amplifier.

The range covers four cabinet and driver sizes, using 10-inch, 12-inch, 14-inch and 16-inch woofers, with amplifier peak capability described from 600 watts in the smallest model to 1.6 kW in the largest.

The subwoofers use Klipsch Cerametallic cones, front-mounted Aerofoil slotted bass-reflex ports and thick MDF cabinets on shock-absorbing feet. Wired RCA connection is supported, while wireless operation is possible with the optional Klipsch WA-2 subwoofer kit. For amplifier buyers, the practical takeaway is simple: bass reinforcement here is self-powered, so the main amplifier does not need to drive the subwoofer directly.

Boulder’s 851 monoblock power amplifier and 808 MM/MC phono preamplifier extend the company’s 800 Series with compact components intended for high-end systems.

The 851 is a single-channel power amplifier based on engineering principles developed for the Boulder 861 stereo power amplifier, while the 808 serves vinyl users with moving-magnet and moving-coil cartridge support.

The 851 is specified at 100 watts into 8 ohms and 200 watts into 4 ohms, with peak power up to 350 watts into demanding 2-ohm speaker loads. The source also notes Boulder’s Smart Current output stage, described as intended to provide wider bandwidth, lower distortion and improved current delivery. Together, the 851 and 808 speak to buyers building a compact but separates-based high-end system.

AVM’s PH 3.3 and PH 5.3 are phono preamplifiers rather than power amplifiers, but they are central to any vinyl system that needs proper cartridge matching before the signal reaches a line preamp or integrated amplifier.

The two models share core controls, connection options and a modular expansion system, while differing in the final gain stage.

The PH 3.3 uses a transistor-based final stage developed with attention to low noise, while the PH 5.3 uses a tube circuit for final amplification. Both provide five sensitivity settings and allow cartridge-related adjustments from the listening seat. That makes them especially relevant for systems using more than one cartridge type or for listeners who value adjustability without repeated trips to the equipment rack.

The Riviera Audio Labs APL1 is a tube line preamplifier operating in Class A.

Compared with the more compact APL10, the source notes that the APL1 adds a tape loop and an additional XLR input, while its larger enclosure allows a bigger power supply and a more complex capacitor mix.

Connectivity is generous for a line stage: the APL1 provides two pairs of RCA outputs and one XLR output, all usable simultaneously with the same gain factor. It uses output transformers for both RCA and XLR outputs, offers relay input switching, includes a remote control for volume, and has dimmable front-panel LEDs. The supplied JJ Electronic tubes can be replaced with other matched pairs, though the source notes this may alter tonality.

PS Audio’s Signature PMG M400 and M800 are dedicated mono power amplifiers in the PMG Signature range.

Each chassis drives one channel, giving each loudspeaker its own amplifier rather than sharing a stereo chassis.

They sit alongside the company’s Signature stereo power amplifiers for buyers choosing between stereo and monoblock layouts. The M400 is rated at 1 x 400 watts into 4 ohms and 1 x 200 watts into 8 ohms, while the M800 is rated at 1 x 800 watts into 4 ohms and 1 x 400 watts into 8 ohms. Both models operate in Class A at lower output levels, with the M400 remaining in Class A up to 30 watts and the M800 up to the higher stated Class A operating region described in the source. The supported distinction is clear: the M800 is the higher-output option, while the M400 is the smaller monoblock in the same family.

The Hattor Audio Takman REX AMRT is a passive and active preamplifier built around two high-precision Takman REX AMRT carbon-film resistor attenuators.

It can operate as a passive preamp and input selector, but also includes an active buffer stage using two OPA2134s.

Connectivity is broad: the source lists two RCA inputs, three XLR inputs, two RCA outputs and two XLR outputs. The active stage can be switched by remote control and offers three gain levels of +3 dB, +6 dB and +9 dB. Separate switchable potentiometers allow left and right channels to be controlled individually or combined with individual levels, which gives this preamp an unusually flexible operating brief.

Monitor Audio Hyphn is a loudspeaker entry rather than an amplifier, so it should not be read as an amplifier recommendation.

Its inclusion is still useful in an amplifier buying context because speakers of this scale can influence the choice of power amplifier, system layout and room planning.

The source describes Hyphn as a flagship speaker system with a mid/high-frequency array linking two bass towers. Each speaker stands almost 140 cm tall, weighs 106.9 kg and uses eleven drivers. The stated frequency range is 18 Hz to 60 kHz. The design includes a third-generation MPD tweeter, six two-inch midrange drivers placed closely around it, and four eight-inch woofers arranged in opposing pairs. No built-in amplifier is specified in the supplied material.

The Naim Audio NAP 500 DR is a stereo power amplifier from Naim’s reference 500 Series, supplied as a dual-box configuration with the NAP 500 PS power supply.

The source emphasizes careful assembly, high-grade component collaboration and technologies derived from the company’s Statement amplification work.

Its output power is listed at 140 watts per channel into an 8-ohm load, and the amplifier is described as withstanding drops in load resistance down to 2 ohms without noticeable performance impact. The NAP 500 DR uses NA009 output transistors and Naim Audio DR discrete-regulator technology. It also supports bridged power-amplifier configuration, making it a serious separates choice for systems built around dedicated preamplification.