Noise and distortion on with MJS USB Audio Selector?
Does anyone have any experience using the MJS USB Audio Selector with their Car PC successfully? I just purchased one and tried to test it for basic function on my test bench. I loaded the drivers and plugged an iPod and a couple of SANSA players as signal sources. I used a cheap set of earphones to listen to the output. I used the software app Mitch includes to check switching function without integrating it into my software front end. (I have both RR and Centrafuse on my evaluation system.)
The selector correctly switches between inputs using Mitch's app. The problem is that the sound is horribly distorted and attenuated when listening to the output on earphones. I noticed that if I 'jiggle' the 1/8" male connectors while inserted in the input jacks, the sound intermittently improves and degrades. It seems like a problem with the jacks themselves. I tried using different sets of cables and ruled out a problem with my cables. I have not tried contact cleaner on the jacks yet.
I looked inside the case and expected to find some small relays. Instead, the design uses semiconductor switching IC's. I wonder if this is part of the problem and I also wonder how good the audio quality can be using IC's to switch the signals. There can't be much signal headroom in this type of design when it is USB powered. Still, the inputs should not be driven into clipping with the output from an iPod or SANSA Fuze. My next step is probably going to be testing the input vs output signal quality using Praxis. I am curious to know if any other forum members interested in sound quality have tried this unit and what their experience has been.
I tried posting a message on MJS website forum but could not do so without registering. I followed registration instructions but have not received an activation email message yet.