Solid State Preamp Reviews

Sidebar 1: Multichannel Application

I am, by preference but not exclusion, a multi-channel guy and, while the LA4 is a two-channel line amplifier, I wondered how using three LA4s might work for my 5.1 setup. It seems that Benchmark does this for show demonstrations, so they were quite willing to accommodate me. The physical setup was trivial, with the first LA4 handling the front L/R channels, the second LA4 the center and sub, and the third LA4 the surround L/R channels. Because the LA4 uses a discrete relay-based stepped volume control, Benchmark said that the three LA4s clustered together should respond synchronously to the remote control. They did, most of the time, when I was careful with my aim. However, there were problems when I was aiming the remote control over my right shoulder from my usual listening spot. The displays indicated any discrepancy among the units, but correction required me to get up and tweak a knob on one of the LA4s.

The synchronization of the volume controls was a bit of a problem with the three units, but there is a simple and inexpensive solution. With a little searching on the internet, I purchased an IR receiver/splitter (about $20). This little box accepts a tiny wired IR sensor as input and has four tiny wired IR transmitters as outputs, each of which attaches to and covers the IR sensor on one LA4. Now any IR signal from the remote control gets to all the LA4s simultaneously, and that includes volume control and all other remote functions. It ain't perfect, but it works well with some opaque tape over the transmitters to make sure that no IR signals leak into the Benchmark. Need more channels? Get more transmitter wires: The box will accommodate up to 12.

The stack of LA4s was a delight as a multichannel preamp and is easily extensible to eight or more channels. There is no pure-analog, fully balanced, multichannel preamp on the market at this time, and it is not likely that one will appear. I am not sure I would go this route, but stacking LA4s does offer a valid if somewhat lavish DIY solution.—Kal Rubinson