USB Connection Probs


Hey folks.

I got my KS Backer Sprout a few weeks ago. My little Xmas bundle of joy.

I’ll admit, I am an audiophile newbie, so be patient…

I am having problems connecting my Mac to the USB input. The instructions say just plug it in and it works, which is generally how everything works with Apple products. I am running OS X 10.10. The latest iTunes and everything is updated. I am sure there is some super basic setting I am not seeing, but any help getting the USB to work would be great.

Also, will USB sound any better than BT? Does it really matter how you connect to it?





After you connect your Mac via USB, open the “System Preferences” (under the Apple Shaped Menu Bar) and select “Sound”. There are three top menu choices (“Sound Effects”, “Output”, “Input”). Select “Output”. From the menu selection select “XMOS USB 2.0 Audio Out” instead of “Internal Speakers”. You should now hear your iTunes via the Sprout (Assuming you have selected “Digital” on the Sprout’s input knob). If you want to further configure the Mac, go into “Applications/Utilities” and open “Audio MIDI Setup” utility application but that shouldn’t be necessary if you just want to get started.

Generally the highest quality digital sound will come from either the SPDIF Coax connector or the USB. Bluetooth bandwidth is quite limited. You might not notice the difference at first but with continued listening you will notice that CD quality or better source material sounds better over the USB or the Coax connector.

Good luck



Go into Applications/Utilities and open Audio Midi Setup. The Sprout should be in the left panel and you should set the output to the Sprout. If you are just playing CDs you’ve ripped, set it to 44.1 kHz and 16 or 24 bits. The Mac will up or downsample to whatever is set here. If you plan to play any high resolution files, I suggest getting an add-on program like BitPerfect. It runs with iTunes, costs $10 from the Mac App Store, and will put out files in their native resolutions.

Bluetooth is very bandwidth limited. You should get significantly better sound using the USB connection.


Thanks a lot guys. I got iTunes playing right away and listened to Royal Blood, which sounded great! Then I added Bit Perfect as suggested. That really opened up the mix! Wow. I wasn’t ready for that. All I heard was the space in the music, which I love. I switched to Midlake’s “Antiphon” album, which uses a stunning combo of acoustic/electric/synth instruments and harmony vocals. I know this album very well, so I immediately noticed the difference.

I have a feeling this Sprout is the start of a very expensive hobby. FML. LOL.

Seriously tho, thank you for the help.


Hello Folks at PS audio:

Happy new year 2015! My name is Oliver Kuo from Taiwan. I got my Sprout before Christmas. Nice product.

However, it failed to output via USB after connecting to my iMac. Therefore, I believed, I have not enjoyed the full power of Sprout sound quality.

Devices: iMac 27" 2009, OS X 10.10, iTune 12.0.1. Sprout with Audioquest 3m ‘Forest’ USB.

Failure Mode: Clean start-up at iMac and Sprout, output via “XMOS USB 2.0 Audio Out”, music comes out around 1 minute(sometimes 1.5 minutes, randomly after every clean restart and Sprout on-off) then no sound. iTune continues running. Switch back to “Internal Speaker”, music is back. If switch to “XMOS USB 2.0 Audio Out” again, no sound.

My 4 USB port at iMac are all functional. No matter I use any of them, same issue.

Last weekend, I re-install OS X 10.10, the problem is not solved.

Need your help!



Sounds like you may have a marginal USB cable. For the sake of troubleshooting try a new cable that is (ideally) < 1m. The long ones have more difficulties in my experience. Good luck.


Thank you, Andrew,

I did your way for a new USB <1m, no luck at all. After 3 minutes of music(with a little noise at the end), the sound is off. Second try, after Sprout on-off, 1 minute. Frustrating.

Anyway to find out if this a problem from Mac or Sprout? Does anyone have a same issue?

Kindly help.



Not sure how familiar you are with the Un*x underpinnings of Mac OSX but if you are up to it, try the following:

  • Open a terminal window and issue "$ cd /var/log".
  • Make sure as few USB devices as possible are plugged in. Turn on your Sprout and connect the Sprout-side USB cable. Do not (yet) connect the Mac side.
  • From the terminal, type "$ tail -f system.log". A bunch of messages should scroll and then stop.
  • Plug in your Sprout. You should see a message on the terminal similar to "USB Sound assertion..."
  • Other messages should scroll by unrelated to the USB audio subsystem. Play some music and wait the requisite 1-2 minutes until the problem happens. Look for messages on the terminal related to USB.



I’m an “Icon-Oriented” user; terminal command lines are far away from my daily life. Thank you for detailed instructions.

I tried 3 times last night connecting to iMac. Mixed results. 1st time, it failed after 3 minutes. 2nd time, 5 minutes. 3rd time, itunes continued around an hour till i shut down the system. No hardware changed(except that 2nd time accidently inserting iPhone for charging). USB are only for mouse and Sprout.

As for the log -
A. There is NO additional USB-related message before and after issue happened(actually no additional lines showed up…).
B. When USB plug-into iMac, message did not show “USB Sound assertion…”, instead, it showed “Found Camera device…”

I also do a little test that, once plug-out USB and plug-in again, it could never be back to same status(at iMac, no “XMOS USB 2.0 Audio Out” showing at Sound configuration) except Sprout power on-off.

Your thoughts?



Ugh! The only other thing I can suggest is to borrow some other USB audio device and connect it to you Mac to see if the problem persists. If it doesn’t then the issue might be with your Sprout and it’s time to get on the phone with PS Audio support. Sorry I can’t be of more assistance.


Andy, doesn’t Oliver’s problem sound a lot like the problem I was having when I was plugging into a USB on my external monitor as opposed to a USB directly on my Windows 7 laptop? Music would play for a minute or two, then stop.

Oliver, can you clarify which USB port you are using on your iMac? Is is directly on the iMac itself, or is it by chance a USB port on the keyboard, which is then attached to the iMac via another USB? Be sure to try using a USB that is directly on the computer itself, not through a secondary USB connection or hub.

I also got a more expensive USB cable than the one I had been using…I think it was an emerald USB DAC cable for about $35 on Amazon. But I think the primary issue was connecting through two tiers of USB connections (Sprout to Monitor, then Monitor to Laptop).


Hello Andy, Jpultorak, thanks for your diggin.

The usb line is directly connecting to my iMac. Not via keyboard or usb hub.

Today I did not have much luck to finish a song playing. Also, I found out that the timing of song noising(not broken) is identical to Bluetooth signal missing. How do I know that? It’s because Apple keyboard is connecting via Bluetooth. The signal is up-down when Sprout Bluetooth connected to my iMac.

At this point, It’s suspicious that Sprout has some kind of transmission problem.




New to the forum having bought a kickstarter sprout

Have taken all the above advice (sound application in setting, bought bitperfect through app store etc) and last night i got nothing.

this morning it all seemed to work ok.

One question? Should the volume controls on my mac keyboard control the volume on the spout as well (they do). I would have thought that if the mac was feeding digital sound into the sprout it would not be controllable from the Mac, just from the amp.

Thanks in anticipation of reply


The Mac USB Audio driver will allow control of the DAC’s volume attenuator if the DAC supports that functionality. Otherwise the control will be greyed out (or occasionally slide around uselessly). The DAC in the Sprout does support this, thus both the master volume control as well as the iTunes volume control both work. The keyboard shortcuts by default control master volume so they work as well.

That said, I usually recommend leaving the volume sliders all the way up and controlling the Sprout with the volume knob. (It’s a long topic and with a 24 bit DAC, no longer as critical a consideration as it once was when DACs were often only 16 bits)


The “remote” app for JRiver allows you to control the Mac’s volume from your iOS device, thus controlling the volume of the Sprout. Very sweet.


I have another question regarding USB hookup to Sprout. I am using an Audiocadabra two headed USB (separate power and audio USB connections on the computer side going to single USB into the Sprout side) to hook up to a MacBook Pro. All works well except that it won’t allow me to unplug the individual USB power connector. Unplugging this connector should work after initial hookup given that the Sprout uses its own power, but I can’t get this to work with this setup. Could it be that power is dedicated only to the amplifier section and does not apply to the USB (thus requiring additional USB power all of the time)? I really need the extra USB slot on the computer for use, so am trying to see if this will work.

Thanks for any and all assistance,

Tom J


Not sure why. Sprout uses the same XMOS USB input as our other products and should not require the 5v. I am not familiar with your new cable, but it should work.


Many self-powered USB devices requires the presence of the 5V for the purposes of signaling a live host or peripheral. This is why some high end audiophile USB cables that skip the 5V DC signal wires don’t work with all devices.