[REVIEW] Warm Audio WA-412 Mic Preamp

by | Apr 13, 2017 | Best Audio Interfaces

Does the Warm Audio WA-412 4-Channel Mic Preamp & DI deserve a place in your studio rack? Read our review below to see what we think of this new unit.

Even in the digital age, getting the signal that goes into the DAW to be as big and musical as possible can present a challenge. There are interfaces that have nice built-in mic preamps, but nothing beats the real thing. Warm Audio’s WA-412 is the real thing and then some.

In a single rack space unit are housed four individual preamps and DI connections, each with a LED meter input, phantom power, tone switch, phase/polarity reverse switch, a -20dB pad, Hi-z engage switch (for the 1/4” input on the front), as well as gain and output controls. The rear has XLR inputs and outputs as well as 1/4” outputs.

The gain and output controls work nicely together; hitting the gain section with strong signals, the audio doesn’t get grainy or crunchy, it can really handle high SPLs overall, using the output to control the overall level the DAW will get. The tone switch is interesting, as it alters the input transformer configuration from 600 Ohms to 150 Ohms. Condenser mics sit well with the 600 mode, while lower powered dynamic mics work better at 150. This control not only works for the XLR inputs, but the 1/4” input, as well.

Its inspiration comes from the API 3124 Preamp, and while we didn’t have one on hand to compare, this preamp didn’t disappoint at all with what we fed into it. The overall response is smooth, and tight. There’s no extraneous audio “fluff” happening that clouds things. And the simplicity of the controls, with a well-tuned design means no looking for workarounds. It can tame high volume sound sources such as guitars as well as drums, while maintaining a nice smooth musical response. And running line outs to your interface means you can still work in the digital world, just with the benefit of better pres going into the session.

So, what makes this so good? Well each channel has its own individual circuit board, and Warm has worked with Altran, who makes their transformers, to really tailor the circuit to their needs. Considering it handles high SPLs well, it’s not surprising a huge toroidal transformer supplies clean power to the four inputs. For real tone tweakers, the 6-pin op amps are socket-mounted and can be swapped out with other versions (not included) for even more tonal customization.

At $1200 it’s almost a bargain, considering there are so many companies making new versions of classic preamps for way more than this, and usually will have only one channel on board. The Warm has four that sound equally fantastic; it’s simple math. With a lot of DAW interfaces coming standard with 8 inputs, a pair of these could easily give that classic sound to all of the channels you want to record, covering a drum kit, horns or background vocals easily. But just one of these could easily make a bigger difference, tonally, than double the cost of any plug-in package could. We recommend you give the new Warm Audio WA-412 a serious look as the cornerstone of your new home studio build.


Classic, smooth sound, well designed.