Topic: Strange interaction between PT and Audacity

Just in case anyone else runs into this and someone can explain why.  I control a MacbookPro via usb midi from the ES7, usb out via FiiO DAC to Presonus 5 monitors.  PT5 output set to -6dB, DAC to 52, monitors to 0 gain.  Works perfectly.  Recently, when editing a recording in Audacity, again via the DAC and the monitors, I turned the Audacity output volume down to avoid disturbing my wife: I didn't need volume for what I was doing. Audacity is not normally running when playing.

Returning to playing, the volume was way down.  Even making sure Audacity was closed and even after restarting the whole setup the playing volume was down.  Only when I opened Audacity and restored the output volume did the playing volume get back to normal, yet Audacity is not in the output path.  Surely cannot be when it's not even running.

Must be a logical explanation.

On the same subject, there are only 2 usb slots on the Mac, I use LH usb for input, RH usb for output.  I once accidentally used the "wrong" slots for the usb in and out cables.  Result: huge increase in playing volume.  Clearly usb slots are not all equal.

Any thoughts/explanations welcome.

Re: Strange interaction between PT and Audacity

That slider controls the system volume, explaining why everything else sounded so quiet.
Far from ideal behavior when trying to keep the audio level with another audio source, I know .

Re: Strange interaction between PT and Audacity

Many thanks for this.  It's crazy that a single application could change a system setting.  However, unless I'm missing a fundamental point, output via usb is digital, the DAC converts to audio and amplifies it.  Not sure how a change to an audio output (in Audacity) can change a digital signal from PT.  Maybe I'm just showing my lack of knowledge about digital/audio principles!