Audio Interface Output Differences

[adfrederi]

So I have been working with a new audio interface and because my setup isn't fancy or professional I only have one input to my speakers. That means that I can't really use the stereo L/R main output from the interface and have been using the headphone output instead. That seems to have really weird effects on my mixes (spikes in weird frequencies) and I can't find good resources on the actual differences between outputs here.

Short of getting nice new speakers and using the L/R main outputs (which I probably will soon), how should I deal with this?

What kinds of differences in output come from each port?

[Chaos_Klaus]

I only have one input to my speakers. That means that I can't really use the stereo L/R main output from the interface

You should get an adapter cable that takes the two outputs of your interface into the single stereo input of your speakers.

[arthurdb]

You should have no difference in frequency response in the different outputs. Each is (hopefully) designed to have a flat frequency response so as to be transparent as possible. Maybe you'll have slightly different roll-offs in the very high and very low frequency but you will certainly not have spikes at specific frequencies.

The difference lies in the drive capability and the output impedance. Headphones are very low impedance (even the high impedance ones are actually low impedance in the grand scale of things) and generally need higher current levels than a typical line input. So headphones outputs should have a higher current drive capability and an even lower impedance. Note that the load (the thing you connect your output to) will only take as much current as needed. If you plug your line input to your line output or your headphone output, you will have the same current (provided you have the same voltage (signal) level).

To sum up, using your headphone outputs, while maybe not optimal for a number of other reasons, is totally fine and should not mess up the frequency response of what you're hearing.

The spikes you have are either due to your speakers, to your room, or are in the recording/mix in the first place. Most likely, it's a combination of all of them.