Proper Connections between Digital Piano and Audio Interface

Question

One digital piano I have has an Aux-Out L/+R and R connection (1/4 inch). I'm looking to use a 2i4 or UR242 interface. Would it be wise to use to 2 cables (balanced?) and connect to the 1 and 2 inputs of the interface, or is a single cable out from the L/+R output good enough? In this case I'm looking to record the sound coming out from the digital piano.

Or is it better to use the output from the headphone jack? I ask this because I have a second digital piano with just that output, no Aux Out.

Similar question on feeding a single back into the first digital piano. It has an Aux-In L/+R connection. With the interface connected to a computer and running Pianoteq, I'd like to output that from the interface into the digital piano at times. Similar question 2 cables? vs a single cable connected to the L/+R socket.

Thanks!

Answer 1

If both the outp[uts and inputs are wired for a balanced connection, you can use balanced (TRS) connectors or unbalanced (TS) ones. Balanced will give theoretically better quality. In practice you're unlikely to hear any difference.

If you want to hear the piano in stereo, use the two output jacks to a pair of inputs on yopur audio interface. If mono is sufficient, you can use just the L+R jack into a single channel. (Same answer for the audio feed back into the piano.)

The 2i4 has only two input channels. If you use them both for stereo piano, you can't use one for simultaneously recording a voice or other instrument.

Stereo can be impressive on solo piano. It can be unnecessary, even annoying, in a mix. Your choice. But if you're recording ONLY piano on this pass, might as well record stereo and keep your options open.

The UR242 has four input channels.

Answer 2

Question 1: use two cables. It sort of depends, but generally electronic pianos sounds best when listened to in stereo. So you would probably want to record it in stereo. This means two channels, and best place to do it is from the Left and Right output on the piano going to left and right input on the interface.

But, then again, you might have and even better stereo plugin inside your computer, then use that on one of the signal.

Question 2: probably two cables or a stereo cable. It depends on what input the piano has: if is a mono input, there is no need to have more than one cable. It could be a stereo input (read the manual), then you are better served with a stereo signal.