No audio output problem?

If you encounter no audio or a humming sound when connected to the TESmart KVM switch,  we suggest trying the following troubleshooting steps.  If the issue persists, please reach out to the TESmart Customer Service Center for further assistance. You can contact us through the chat window at the lower right or by submitting feedback. Our dedicated team of professionals is ready to help and provide after-sales support.

Applicable product model: All of the KVM switches,

HKS202-E23 (Previously HKS0402A1U)/HDK202-E23 (Previously HDK0402A1U)/
HKS202-P23 (Previously HKS0202A2U)/HKS402-P23 (Previously HKS0402A2U)/
HKV202-E23 (Previously HKV0402A1U)/HKS802-E23 (Previously HKS0802A1U/
DKS802-E23 (Previously PKS0802A10)/HKS0403A1U etc.

This article includes the following topics:

In the event of no audio output, the first step is to determine the pathway for transmitting audio (either through decoding audio via the video port or outputting audio through the USB channel).

  1. For products with HDMI output interfaces and only L/R ports, the audio signal is decoded from the HDMI channel and then output through the L/R ports.
  2. For products featuring dedicated microphone or headset interfaces, the audio signal is transmitted via USB.
  3. For products with DP output interfaces and L/R ports, the audio signal is transmitted via USB.
Below is a table detailing the audio transmission pathways for our main KVM Switch models. If you can not find the information you need, please contact our customer service for assistance.

We have outlined detailed troubleshooting steps below, Please refer to the following suggestions for assistance:

When transmitting audio through the USB channel

  • Please make sure that you have selected the correct USB audio device in your computer's audio settings. Typically, USB audio devices connected to the KVM switch are recognized as "USB Audio Device" on your computer settings (though occasionally they may be recognized by a different name). Alternatively, you can unplug and plug in the audio device to confirm that the newly recognized device is the one you need to select.Audio-1.JPEG


  • Make sure the audio device you are using has a USB power cable. If your audio device comes with a USB power cable, please connect the USB power cable to the USB 2.0/3.0 port on the KVM and check if the audio can be output normally.If your audio device does not have an additional USB power cable, please try connecting the audio device directly to the computer and check if it works properly. If it still doesn't work when directly connected, it may indicate an issue with the USB audio device itself.
  • Please verify if the standard USB 2.0/3.0 port on the KVM is functioning abnormally. Please try connecting another USB device to the USB 2.0/3.0 port on the KVM switch to check if it is working. If no devices work properly when connected to this port, it suggests a potential problem with the USB 2.0/3.0 port on the KVM.

  • Please check if the USB audio device has driver issues. Please open the Device Manager on your computer and check for any abnormal driver-related issues (devices with exclamation marks) related to the USB audio device. If you encounter such issues, please visit the official website of the sound card or amplifier device to download and install the latest drivers.
  • When outputting audio and video signals through the VGA port on the PC, please avoid mistakenly connecting the audio cable to the microphone input port. Since the VGA port can only output audio signals, you will need a VGA to HDMI converter and an additional audio cable when connecting. The PC has separate audio ports for microphone input and left and right audio channels. Make sure you select the correct left and right audio input ports and not the microphone input. In addition, please directly select the name of your amplifier device as the selected audio channel on your PC.

When transmitting audio through an audio interface

  • Single-monitor KVM: When the computer does not select the audio output channel for the corresponding display device: When using an audio device connected to the KVM, it functions as if there's an integrated audio device on the monitor. Therefore, please select the name of the connected monitor as the audio output channel in your computer's sound settings, rather than the name of the audio device, and then verify if the audio can be output normally at this time.


  • Multi-monitor KVM: The correct audio output channel is not selected. Multi-monitor KVMs only have one audio output channel corresponding to a single monitor that can output audio: Please choose the name of the monitor connected to either display 2 or output B port as the audio output channel. If there are multiple monitor names appearing, try selecting each of them one by one in your computer's sound settings. Please confirm selecting one of the monitor names as the audio output channel and seeing if the audio can be output correctly.
  • Abnormal Audio Device Usage: Please attempt to connect this audio device directly to the computer to see if it works properly. If it doesn't function correctly when connected directly, it indicates an issue with the USB audio device itself.

Troubleshooting for Other Audio Issues:

  1.  Abnormal Sound with Electrical Noise: Reinsert the audio cables connected to the audio interface and the USB power cables connected to the power supply interface to ensure that the ground lines between all devices are properly connected.
  1. Intermittent Sound: This issue may be due to loose cables or insufficient power supply. We recommend reconnecting the cables or using a dedicated USB power source for troubleshooting.

How to Adjust Mac Audio Output Device Settings

  1. On your Mac, click the Apple menu, then select "System Preferences." Next, click "Sound," and then click "Output." (Alternatively, click the trumpet icon in the menu bar.)
  2. Choose the desired audio output device from the list of sound output devices.
  3. The list includes all available sound output devices on your Mac, such as the built-in speakers, the display device connected to your KVM, USB speakers, and AirPlay devices.
  4. Please select the name of the monitor as the audio output channel. (If you are using a multi-monitor KVM, choose the name of the monitor connected to the display 2 port or output B port.)
If all of the steps above cannot help you locate and resolve the problem, please contact TESmart Customer Support for further assistance. Briefly mention the steps that you’ve already tried for a faster solution.


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