colito wrote:...the sound quality out of the 3.5mm jack is terrible and I suspect this may be due to noise from other attached devices. I've tried a couple of different wireless adaptors and power supplies but can't seem to get rid of it...
A good WiFi adapter and a solid power supply will always be a good investment if you are doing anything with your Pi that involves sound or an analog signal.
Unfortunately, you can't solve the problems with the 3.5 mm output that way. People have wasted huge amounts of time and money trying to improve or filter that output, and it just can't be done. At best you can change how it sounds, but you can't put back in what is not there at the source, which is inside the Broadcom chip.
https://www.reddit.com/r/raspberry_pi/comments/2yu3kd/rpi_2_poor_audio_quality/For HiFi music, the sound quality at the 3.5 mm jack will always be poor compared to other options. The main reasons are the audio conversion method and noise from various sources.
The Pi uses the PWM conversion method (pulse-width-modulation) to produce the sound output at the 3.5mm jack. The implementation is pretty basic, and the quality is probably equivalent to ~10 bits at maximum volume. The distortion is pretty bad.
http://www.crazy-audio.com/2013/11/quality-of-the-raspberry-pi-onboard-sound/Second, for audio purposes there is a lot of noise present on the Pi, starting with the power supply, the voltage regulators, the PWM circuit, and on from there. This results in a really poor SNR (signal-to-noise-ratio) when the 3.5 mm jack is used as a line output.
By comparison I2S and USB DACs usually use a separate dac chip, a separate voltage regulator, and other tricks to keep the noise down.
). The cheaper one can then be used in my kitchen set up.
