DAC - do not plug in with power on


I just bought a DirectStream DAC and P15. On the back of the DAC a sticker was present over the power receptacle stating “do not plug in with power on”.

My plan was to plug everything into the P15 and after powering all my equipment down after a listening session (if I didn’t plan to listen again for days) I would then turn off the P15. I do this as I’m not a big fan of leaving my equipment on endlessly if I don’t plan to listen for stretches of time. However, turning off the P15 will kill the power to the DAC and therefore I must turn off the DAC on the front panel and then also turn off the DAC on the back panel to be ready for when I next turn on the P15. What a hassle. The rear panel switch is not easily accessible. And I don’t want to leave the P15 in active mode. I want it to be completely shut down like the rest of the equipment.

What have other people done? Are all people either leaving the P15 in active mode to keep power going to the DAC or doing the rear panel power down of the DAC each time they turn off the P15?


I leave my regenerator on and DSD is on standby. This is the recommended way to leave the Dac powered.

Leave it on. What’s the big deal? All stereo equipment I have owned sounds best hot. I had a Benchmark DAC that didn’t even have a power switch.

Regarding the warning about not plugging in with the switch on… well fine… but what about the reality of a power failure? PS Audio didn’t think this one through.

Bruce in Philly

Plugging in with power on isn’t the same as having something up stream powering on or off. Internally the DS power switch is simply that: a switch on the hot leg of the power and doing that in the DAC or upstream doesn’t matter at all. Plugging in with power on hooks up the safety ground, the neutral leg and the hot leg in random orders and can cause bad current loops thru the interconnects, etc.


Ah, that makes sense! I had been wondering about that sticker too. I’m pretty anal about turning things off before unplugging (and certainly plugging in), but I had never seen such a warning sticker before.

It’s good practice to turn your power switch off before plugging or unplugging anything.

Thanx for that Ted… things are always more complex than first appear… Since you are good at answering questions about complexity… how about examining my marriage? What are your rates?

Bruce in Philly

Teds rates for married audiophiles are off the charts… :laughing:


I’ll bet Ted’s first piece of advice for a happy marriage would be:
First–grow one of these beards


Ted, just to make sure I follow what you are saying, as I’m not sure I do - it’s okay to leave the DAC rear panel switch on while powering up and down the P15 output receptacles (of which one receptacle provides power to the DAC)? I assume we consider it okay as we assume the internal design of the P15 is such that the ground and neutral leg are uninterrupted by the powering on and off of the P15 receptacles - which I can check later tonight to see if that assumption is correct. It should be for the ground, but I’m not so sure it would be the case for the neutral given the P15 is regenerating the power signal to remove noise and such.

I have a couple of other questions. Shouldn’t DAC come up in stand-by mode when power is initially supplied to it, therefore providing power isolation to the much of the circuity and interconnect? Then only when the unit is brought out of stand-by mode (by the front panel stand-by switch being pressed) would the power propagate? A second question is; couldn’t the upstream power supply ground, neutral leg and hot leg connect in random orders when an upstream powering-up and down occurs and therefore cause the same unwanted current loops to occur and therefore pass right down to the DAC and result in the exact same current loop situation? Thanks very much for your thoughts on this matter. Alan.

I blew the fuse once and then switched the power off in the DSJ ever since. as the button is not easily reachable in the back I made sure the power cord connects to a switch I place besides the DSJ, not particularly beautiful but it works.


Standby mode doesn’t turn off (or on) power inside the box - there aren’t any relays or whatever that would power down some sections of the hardware. Standby hardware mutes the outputs and turns off the screen.

Surely you aren’t considering unplugging the P15 and plugging it back in while it’s powered on and feeding other powered on devices? Or are you asking if the P15 hooks up the output wires in a random order when it’s powered on or off? It doesn’t.

True, true. I have mistakenly pulled the plug out of the back of my BHK Preamp once. Not a catastrophic event mind you but still enough of a pop through my speakers to make sure I haven’t done it again!!

Here’s another thing to consider: If you do that and there’s an audiophile fuse such as a “Blue” (which I believe DO sound better), it will likely pop. They seem to be built with zero inrush tolerance. (Just my wild ass guess based on experience)