Sending computer audio output to guitar amp instead of monitors?

  • I have a pair of Focal monitors which I used for mixing and general audio playback from my computer (Mac Mini i7 quad core). I plug in guitar to my audio interface which is a MOTU 4pre via Firewire/UAB to the Mac. But as a guitar player nothing beats the power/sound of a real amp. I love BIAS FX2 pedals and all but listening back via monitors could be better.

    I'm wondering what the best way would be to send my computer signal out to a guitar amp, so basically audio out from Mac (mini port) to 1/4 to the amp..any suggestions?

  • @macgringo

    It wouldn't come from the Mac mini port -- that's what the MOTU is for (to act as a DAC). If you have an effects loop on your amp, then it's not much different from connecting your outputs to your monitors, only the monitors are stereo (and two cables), while the amp is mono (and one cable).

    I remember looking at the 4Pre awhile back -- from what I remember, the 4Pre has a second set of line-level "Outs". So if your amp has an effects loop, then you can just go from one of those jacks (for instance, "Out 3") to the "Return" jack on your amp's effect loop. Then configure the DAW track or standalone BIAS-FX to use "Output 3" (mono).

    Also, in the BIAS-FX Global "Output Settings", along the top section of this settings window, you'd need to change the output from "Direct Out" to "Combo Poweramp" or "Stack Poweramp" (whichever is applicable to your amp setup, although I think by default they are the same), since your physical amp is now providing the poweramp and cabinet stages. You also need to enable "Output Settings" in the main window, since it is off by default.

    If you don't have an effects loop on your amp, the line-level outputs aren't meant to go directly into an instrument-level preamp jack on the front of an amp, since the signal would be "hot", with a lot of noise. The same would be true of any DAC line-out used with your Mac, not just the MOTU. There are workarounds, though, better explained here:

    Note if using a regular guitar input on the front of the amp -- in the BIAS-FX Global "Output Settings" mentioned above, you now want to instead select "Amp Front". There are several scenarios and combinations here, depending on your intentions, but that's the typical setup.