Only the Momentum HD preamplifier offers the sound quality and drive necessary to maximize the possible performance of the Momentum M400 monoblock and Momentum S250 stereo amplifiers. The Momentum HD preamp is based on the award-winning Momentum preamp platform. The new HD state represents the high-definition and high-dynamics enhancements that have been achieved in this major update.

Advances in audio circuitry, power supply, and control sections are incorporated into the new Momentum HD preamp. Like Momentum amplifiers, the preamp uses a complementary balanced circuit topology for maximum bandwidth and low noise. Its audio circuitry is totally discrete, with no operational amplifiers. The zero feedback design ensures the highest quality of musical sound. Volume adjustment is done through a resistor network governed by an optical controller, the cleanest and most transparent method possible to control volume.

A completely new discrete differential FET input stage features two current sources per leg and an input impedance of greater than 1MOhm. This ultra-high input impedance isolates the input stage and thus the entire audio signal path from external variables. This new entry stage began as an engineering exercise that produced exceptional results. Fine-grained details and delicate musical nuances are rendered with an exuberance and richness that was simply unattainable before.

The Momentum HD main power transformer, housed in a separate chassis for maximum isolation, is 33% larger than the original Momentum preamp. A unique winding technology, first used in the Momentum M400 amplifier, delivers increased power output from the same space. The audio power supplies and control circuits are independent, so the control circuits are completely isolated from the audio circuits. Internal circuitry filters RF noise from the AC power line and compensates for asymmetric power waveforms and DC from the main power line. Taking advantage of the increased power supply capacity, the output stages are now operating with 36% more voltage. The increase in the output voltage has opened the dynamics both at the micro and macro level, with contrasts that are striking for their speed.

Also new is the Bluetooth technology that is included in the remote control. The Bluetooth backbone extends the range of the remote control by a factor of five and eliminates the line-of-sight limitations inherent in infrared remote controls. Newly designed volume and tone control circuitry increases range and precision on both circuits. The Momentum HD preamp styling perfectly complements the Momentum M400 and S250 amplifiers, with copper accents that match the amplifiers' unique copper heat sinks. The meter on the front face of the preamp indicates the volume setting, polarity, and mute status. The front selector buttons light up to indicate which input is active.

Owners of existing Momentum preamps will be able to upgrade to new enhancements to the electronics in the Momentum HD preamps.

Technical characteristics:

Inputs 6 balanced stereo XLR

2 balanced stereo XLR outputs

Frequency response 0.1 Hz to 1 MHz, -1 dB, 20Hz to 20 kHz, ± 0 dB

Distortion (full output) <0.006%, 20 Hz to 20 kHz

Signal-to-noise ratio -105 dB, unweighted Gain +13 dB or +19 dB, switchable

Power Consumption (Standby) <1 Watt

Input impedance 1 MΩ

Output impedance 10Ω

Dimensions (preamp) (hwd): 10.8 x 45 x 30 cm

Dimensions (power supply) (hwd): 7.5 x 27.5 x 20 cm (height)

Weight 45kg, with power supply