Benchmark LA4 Rackmount Line Amplifier

The LA4 is 100% analog. It is designed to be driven from external D/A converters and external line-level analog sources, and to drive any professional or hi-fi power amplifier.

At any volume setting, the relay-controlled gain stage provides an optimized attenuator to match the upstream analog source to the downstream power amplifier. This optimization of the gain staging delivers the best possible system SNR for each volume setting. The LA4 matches high-output D/A converters to low-input power amplifiers and vice versa. It also provides an optimized interface to and from balanced and unbalanced devices. In addition, it matches high-level professional balanced interfaces to low-level hi-fi balanced interfaces (in either direction).

The bandwidth of the LA4 extends from 0.01 Hz to over 500 kHz. This means that the LA4 delivers very precise amplitude and phase accuracy over the entire audio bandwidth. Wave shapes are accurately reproduced, and the entire spectrum is delivered with precise timing. The LA4 is designed to deliver musical overtones with lifelike accuracy so the sonic character of musical instruments is rendered truthfully.

The LA4 features two balanced stereo inputs and two unbalanced stereo inputs. The line amplifier provides one balanced stereo output, one balanced mono sum, and one unbalanced stereo output.

The LA4 can be operated using a separately available remote control. The LA4 is designed to work with the separately available DAC2 and DAC3 converters but may be driven from any high-end D/A converter. When paired with a Benchmark DAC, a single remote control will operate both units.

Two bidirectional 12V trigger ports can be used to link the LA4 with external D/A converters and power amplifiers. The trigger signal controls the power-up and power-down sequencing of the entire audio system. The trigger ports are compatible with most industry-standard trigger input or output ports, but can communicate bidirectionally with other Benchmark products.

The touchscreen provides easy access to advanced features such as balance control, input level offsets, input names, screen dimming, remote control, and function locking. Help screens explain the special functions.

The volume control knob features a high-quality optical encoder that is rated for heavy use. An acceleration feature makes it easy to move through the 256 volume steps while maintaining 0.5 dB/step resolution. A press of the control knob will wake, turn on, or brighten the screen if you are using the screen sleep or auto-dim functions.

The LA4 includes an on-screen mute button for the line outputs. The outputs can also be muted with the volume knob or with the remote control.

The LA4 includes an on-screen -20 dB “audio dim” button that instantly reduces the level by 20 dB. This function provides a temporary volume reduction and makes it easy to return to the previous listening level. This control makes it easy to transition between a normal listening level and a background level. The -20 dB “dim” function is also accessible from the remote control.

The inputs may be renamed and unused inputs may be disabled. Input levels can be trimmed to provide input-to-input level matching.

Screen brightness is adjustable and timers can be set to dim or shut off the display. The screen can be locked to prevent access to advanced features.

The case features a milled faceplate and milled sides. Top, bottom, and rear panels are made from thick aluminum and feature a brushed texture.

The LA4 was designed, assembled, and tested in the USA using USA and imported components. Most major components are made in the USA.