This guide will hopefully demystify interconnection of balanced and unbalanced audio devices, specifically balanced outputs to unbalanced inputs. It is in no way comprehensive or complete. For further information please reference the following links: RaneNote 110: https://www.rane.com/note110.html Bill Whitlock’s excellent application note AN-003 http://www.jhbrandt.net/wp-content/...tion_of_Balanced_and-Unbalanced-Equipment.pdf pg 3 balanced to unbalanced interfaces, which is from http://www.jensen-transformers.com/ Consider the following diagram in which it is desired to send a signal from an audio device balanced output on the left to an unbalanced audio device input on the right. Signal levels will be ignored for this example. There are two active outputs on the balanced output presenting opposite polarity of the audio signal. The simplest approach, but not necessarily the best, is a cable employing a female 3-pin XLR to 2-pin TS ¼” plug or RCA plug. Pin 2 from the XLR will connect to center of RCA or Phone Plug. Pin 1 ground on XLR will connect to sleeve on the unbalanced plug. Pin 3 on the female XLR remains unconnected (NC.) So what could possibly go wrong? Plenty, depending on alternate / additional ground paths between the two devices. Power supply noise in the grounds, RFI / EMI, DC offsets between ground references, etc. Additionally there are some balanced devices that use Pin 3 hot instead of Pin 2 hot, though that would only create an inversion in the signal in this example. Without knowing specific implementation details of analog signal ground to chassis ground to mains earth ground for both devices we can’t predict whether this simple interconnection method will produce satisfactory, noise free results. Commercially available adapter cables are fabricated with several different connection schemes. Some are implemented with pin 3 NC as in the example given above and some with female XLR pin 1 and 3 connected as shown below: Depending on the balanced audio device output design and the ability to current limit active devices in the case of output short circuit, the following scenario may develop: This is clearly not desirable, especially for active device outputs. Permanent damage may occur. If unsure, don’t do it. You have been warned. If the balanced audio device output uses transformers, the situation may be reversed. The cable that worked well for active device outputs leaves one side of the transformer output unconnected. This is not going to work well. Connecting XLR pins 2 and 3 is the correct solution for this situation. An external transformer is another option for connecting active device balanced outputs to an unbalanced device input. Many are equipped with a ground switch allowing experimentation to achieve lowest audible residual noise. Which solution is the best for a specific pair of devices requires knowledge about the two audio components connection implementations. It also doesn’t hurt to have a DMM and be familiar with resistance and impedance measurements. The issue of level mismatch, eg. +4 dBu vs -10 dBV was not addressed in this brief visual guide. That is a topic for another post.