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Buzz and hum free PC to Home Theater Stereo with TOSLink and SPDIF

When connecting your PC to your home theater system using the standard 'Line Out' jack on the PC, the end result can be annoying buzzing and humming.

This is due to poor electrical connections or because of the cheap electrionics used on the analog portion of the sound card; from sloppy D/A converter to amplifier section, the standard PC sound system amplifier was designed for use with common PC speakers, not high end audio systems; it causes distortion of the audio signal and picks up non-audio related signals abundent in the PC.

In some cases, the signal quality can be improved by the use of a ground loop isolator. These are commonly used in mobile applications (car audio), and these can be found at most car stereo shops. This can be used when the stereo does not have digital inputs.

Most (not the cheap $200 all inclusive systems) HT receivers and amps have both TOSLink (optical cable) and SPDIF (Digital using a single RCA cable).
Many higher end PCs are shipping with TOSLink capability; the jack looks just like the optical jack on a standard DVD player.

By connecting your PC to your stereo with either of these digital interfaces, several benefits are immediatly heard:

  • Buzz and hum are elminiated
  • Electrical noise from the PC, like hard drives, power supply, and even the CPU are eliminated
  • Easier Listening - Cheap DACs in PC are inaccurate and add overtones to the signal, which can actually cause pain in your ears
  • Fuller Music which is more 'alive' - The DACs in HT systems are far superior to those in PCs, and reproduce the signal faithfully

    • Your PC may not have come equipt with digital audio out capabilities, but it's easy and inexpensive to add with the use of USB Audio Adapters (USB Sound Card), like those sold by Turtle Beach, M-Audio, C-Media, Zalman, Creative Audio.
    These adapter usually have dual-capabilities;analog out and digital out.

    The Turtle Beach Audio Advantage USB Audio Adapter
    Despite its tiny size, it works awesome. With the little pigtail USB supplied, it seems more like just another cable instead of another piece of hardware

    Another advantage of these little USB Audio Adapters is that multiple adapters can be attached to a PC or HTPC, and the PC can playback multiple stereo audio channels. This is particularly usefull with Whole House audio systems, where speakers in different rooms in a house are served by a central whole house audio amplifier. With mutiple USB Audio Adapters, a PC can send different program material to each room.

    With some software hacking, audio players like the open source LittleTux Networked Audio Player for Linux and Windows, one can build a whole house audio server to play MP3 and FLAC files, while using a PDA or Pocket PC as a two-way remote control.

    SPDIF is the non-optical version of TOSLink. It carries the same signal as TOSLink, but uses an electrical signal rather than pulses of light.
    Some PCs have SPDIF.

    To connect using SPD/IF simply plug a single RCA cable between SPDIF out on the PC, and SPDIF or Digital In on the HT receiver.
    Many A/V cable companies (and salesmen) promote expensive RCA cables exclusivly for digital connections, however, regular RCA audio patch cables can work just as well.

    Copyright (C) 2007 by Barry Sprajc - All Rights Reserved

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