Hmm, I've never owned any DAC that had a power switch! So they were just left on at all times out of convenience even if that was a small waste of electricity.On both my Berkeley Alpha and BMC it’s a particular level that’s not all the way up. But mostly what I’m concerned about is that both of those DACs revert to a low volume when turned off. I hate adjusting volume to a particular level every time I turn it on.
The ones with digital volume control did remember their last setting even if I pulled the power cord, but I don't think any of them had a setting for start-up at a particular level, they just remembered their last setting.
Something with vacuum tubes would of course need an on/off switch.