The Mainline is a 300-watt solidstate stereo power amplifier designed to emulate the sound and feel of a tube guitar amp. Rather than providing the relatively flat frequency response typical of most other solidstate power amps, it employs proprietary circuitry designed by LA Custom that enhances specific frequencies for a warmer sound, as well as providing a more tube-like response to playing dynamics.
The single-rack-space unit outputs 150, 75, or 37.5 watts per channel into a 4Ω, 8Ω, or 16Ω load respectively. Bridging the outputs yields 300 watts into an 8Ω load or 170 watts into a 16Ω load. The Mainline may be configured to power any setup from a single mono cab to four cabs in stereo with two cabs per side.
The amp’s front-panel controls are very straightforward. Each of the two channels has controls for Resonance, Presence, and Level. The Resonance control fattens up the low end, the Presence control emphasizes the highs, and the Level control adjusts the output volume.
On the rear panel are two 1/4" inputs and two pairs of 1/4" outputs for Channels 1 and 2. The inputs may be switched from line level to instrument level, enabling you to plug a guitar or bass directly into the amp without a preamp. The instrument-level inputs will also accept the output of a pedalboard, making the Mainline ideal for amplifying the effects in a wet/dry or wet/dry/wet amp configuration.
Also on the rear panel are a voltage switch for selecting 115- or 230-volt operation and a Stereo/Bridge switch for selecting stereo or mono operation. Inside, a very handy Automatic Short Detection circuit powers down the amp should the outputs be shorted for any reason.
I tested the Mainline in stereo mode using a Fractal Audio Axe-Fx II XL preamp and a Yamaha THRC212 2x12 speaker cabinet loaded with Eminence Legend 1218 and Tonker 8Ω speakers. To begin with, I created some preamp-only presets to better hear the sound of the power amp and cab. I liked what I heard, though one preset sounded a little thin, so I compensated by turning up the Resonance controls, which did the trick. Both Resonance and Presence sweep wide ranges, making it possible to easily dial in the optimum frequency balance. Bridging the amp to mono yielded equally good results. Next, I set the Mainline’s inputs to instrument level and plugged the stereo output from my pedalboard directly into them. This, too, sounded really good, and after some experimentation I found that simply keeping the Resonance and Presence controls straight up worked fine.
In both applications the Mainline did indeed sound and respond much like a tube guitar amp, without the stiffness or harshness found in some solid-state amps. At the same time, the sound was fairly neutral, with little of the glassiness, sag, or other idiosyncrasies that add personality to classic tube-amps; and that’s actually preferable if you plan to use it with amp-modeling devices, as the models themselves already possess those characteristics.
The Mainline weighs just over 17 lbs, though some of that heft is attributable to its ultra-roadworthy build quality. It’s also worth noting that for such a powerful amp, it is very quiet and operates at a relatively low temperature. All told, the Mainline is a well-built, flexible, greatsounding amp that’s priced squarely in reach of working players.
PRICE $459 street
INPUTS Two 1/4"
OUTPUTS Two 1/4" (Channel 1), two 1/4" (Channel 2)
CONTROLS Level, Resonance, Presence (x two channels), Power switch, Instrument/Line level input switch, 115-/230-volt switch, Stereo/Bridge switch
POWER 300 watts
EXTRAS Automatic Short Detection circuit
WEIGHT 17.4 lbs
KUDOS Sturdy. Versatile. Tube-like sound and response.