Data-only USB cable : do I keep the ground wire connected?

[Final_Baton]

Hello everyone.
I bought a linear power supply(Teralink U9) for my Peachtree Dac iTx, and it comes with a power-only USB pass-through cable like pictured below that plugs in the linear supply and allows it provide the 5v of power the DAC's USB port seeks, instead of my USB source(my pc in this case) doing it. Now using this pass-through cable, the PC only pumps out the data (and no power, which is handle by the linear power supply instead).

Supposedly this can also help since a PC motherboard won't output a precise, steady 5v, whereas the linear power supply will.

My question is : if I'm to hack the USB cable connecting my PC to the DAC, as to make it a data-only cable, do I need to cut the power wire only? or the ground wire as well?

Also : is this power-only pass-through USB cable thing really gonna have any benefit in my case? (meaning : is this only necessary for DACs that are powered via USB? and does the DAC itX even need 5v coming from a USB cable to be powered? and if not : will this help at all?)
I haven't found info online on Dac iTx users using a USB power-only passthrough with a linear power supply

Thanks in advance for the info! This forum is always of great help.

 

[CoogarXR]

I would think the pass-through cable would already provide a "dead-end" for the power coming from the PC. I wouldn't think you'd need to do anything. Again, just a guess, but you could test it by connecting the bypass cable without turning on the new power supply and see if the PC power still powers the DAC. I bet it doesn't power up.

 

[E.Auer]

Data only (non power) USB cables use the ground as well. So I would not cut it.

Eric

 

[Final_Baton]

Data only (non power) USB cables use the ground as well. So I would not cut it.

Eric

Thanks a lot Eric!

 

[Final_Baton]

I would think the pass-through cable would already provide a "dead-end" for the power coming from the PC. I wouldn't think you'd need to do anything. Again, just a guess, but you could test it by connecting the bypass cable without turning on the new power supply and see if the PC power still powers the DAC. I bet it doesn't power up.

I turned off the new linear power supply, connected the dac back with the old switching power supply, plugged the usb cable (the one that comes from the pc) into the passthrough cable and into the dac. The PC doesn't detect the peachtree at all (usually does within seconds, no drivers required).

Is it safe to say that my pass-through cable provides a "dead-end" for the power coming from the PC, as you alluded to in your first sentence?

 

[gvl]

Wait, the Dac itx isn't USB powered, what are we talking about here?

 

[Final_Baton]

Wait, the Dac itx isn't USB powered, what are we talking about here?

about sending cleaner power to the Peachtree's USB audio input jack. That jack won't work unless it receives 5v from a lead plugged into it (even though the DAC is already receiving it's required 9v through the power connector). Usually, the usb cable you use for connecting the PC to the DAC will provide those 5v. But the 5v sent by the PC is not a very clean power source, it's quite dirty infact and adds noise to the sound, due to the switching power supply inside the PC. Using an external linear power supply to supply those 5v to the DAC's USB port gives a cleaner sound.

In fact I've tried it and it does sounds a LOT cleaner. Very impressive

I just wanna make sure I'm not sending something I shouldn't to my DAC's usb port so as to avoid damaging it in the long term.

 

[Final_Baton]

Oops, double post.

 

[gvl]

Ok, just wanted to make sure I'm on the same page. From what I read the power on the USB power conductors is often only necessary for the initial handshake and can be disconnected once the device is recognized if using a self powered DAC .

 

[Final_Baton]

Ok, just wanted to make sure I'm on the same page. From what I read the power on the USB power conductors is often only necessary for the initial handshake and can be disconnected once the device is recognized if using a self powered DAC .

Yeah, looks like there are some self powered ones out there. Unfortunately, mine isn't one

 

[gvl]

You could as also use Schiit Wyrd as a less hacky solution.

 

[Final_Baton]

You could as also use Schiit Wyrd as a less hacky solution.

Thanks for the recco. That'd make a tidy setup indeed.

However I think I'll stick with the Teradak U9 linear power supply. There's already one wire going from it to the DAC(power plug), so having a second one is not too bad