Pro-Ject Pre Box S2 digital DAC
- Thread starter miero
- Start date
On the UpTone adapter there is a VBUS on/off switch, and with it on it works perfectly (I have it directly connected between the iFi nano to the DAC, no USB cable).
But if I set the VBUS switch to off, and connect 5V power to the DAC with the micro USB input, it does not work. Is the DAC supposed to work without 5V for the USB B input?
JohnW
pfm member
left channel
Prominent Member
@MagnusH that's common with UpTone products. I'm using part of the packaging, folded up, to hold a similar adapter and a USB REGEN in place behind another DAC.
I want to test the S2's USB filtering on its own, so have not used the REGEN with this one yet, except to supply power when I was testing the S2 with my Android phone and UAPP. (The phone was unable to power the S2 on its own, and the S2's external wall-wart did not help, but putting the USB REGEN inline did the trick. The resulting sound was not worth the effort, but it was a fun experiment.)
I want to test the S2's USB filtering on its own, so have not used the REGEN with this one yet, except to supply power when I was testing the S2 with my Android phone and UAPP. (The phone was unable to power the S2 on its own, and the S2's external wall-wart did not help, but putting the USB REGEN inline did the trick. The resulting sound was not worth the effort, but it was a fun experiment.)
left channel
Prominent Member
Thanks @MagnusH for passing the firmware and instructions to me! Productivity was shot dead for at least an hour this morning. 
I did not hear the popping sound while watching the control panel report switching between the 44100 Hz and 48000 Hz internal clock, as I tested a wide range of FLAC files, then internet radio, Qobuz Hi-Res and lo-res streams, and Tidal MQA and HiFi streams. For example, 192 kHz to 44.1 kHz and back again. Also, it sounds great!
I also noticed the control panel's Output Volume controls are no longer greyed out. They work, but silence the sound well short of its full 127 dB range, probably between -30 dB and -50 dB here. You'll find this under "Device 0" via the "Output Channels" button.
I did not hear the popping sound while watching the control panel report switching between the 44100 Hz and 48000 Hz internal clock, as I tested a wide range of FLAC files, then internet radio, Qobuz Hi-Res and lo-res streams, and Tidal MQA and HiFi streams. For example, 192 kHz to 44.1 kHz and back again. Also, it sounds great!
I also noticed the control panel's Output Volume controls are no longer greyed out. They work, but silence the sound well short of its full 127 dB range, probably between -30 dB and -50 dB here. You'll find this under "Device 0" via the "Output Channels" button.
I did some quick testing earlier with and without the iFi nano iUSB3, and the iFi nano gives a increase in sound quality, but when I tested to power the DAC with iFi but connected the USB B to the computer instead of to the iFi nano, I did not notice a decrease in sound quality.
In other words, it would seem that the stable power the iFi nano gives is the main reason for the sound quality improvement (but this was a quick test so take it for what its worth).
With this in mind, I think the best solution from a price/performance is to connect the DAC USB B to the source (computer etc), and use a $50 5V iFi iPower connect to the DAC micro USB.
In other words, it would seem that the stable power the iFi nano gives is the main reason for the sound quality improvement (but this was a quick test so take it for what its worth).
With this in mind, I think the best solution from a price/performance is to connect the DAC USB B to the source (computer etc), and use a $50 5V iFi iPower connect to the DAC micro USB.
Thats to be expected for a DAC of this size and price. There are lots of DACs 10 times more expensive that also benefits from better power.
I am surprised that the regen/reclock feature of the iFi nano does not provide much of an improvement, I guess you handle the cleanup of the USB signal good inside the DAC.
left channel, have you tested with/without Regen and with/without better power, whats your impressions?
left channel
Prominent Member
OK, that will be my next little testing project! Beats workin'.
I don't believe I can run the REGEN without letting it substitute its own USB power, so I don't think I can separately test the signal cleanup and the power improvements though.You can attach the power that came with the DAC, the DAC will autoswitch to the power in the micro USB if its attached. So with that power supplied, you will only test the signal cleanup (compared to USB direct into computer).OK, that will be my next little testing project! Beats workin'.
left channel
Prominent Member
I see, thanks. The manual says not to connect USB and the wall-wart at the same time, to avoid "power disturbances from two power supplies", but I can watch for that. I'll let you know how it sounds with the all possible power and REGEN configurations.
left channel
Prominent Member
According to Brian at Roon, all DACs have a few seconds transition phase until they switch to MQA (he tested with Brooklyn and Explorer2). However, none of them had the stutter during the transition phase.
Tonight I decided to listen to headphones, and tried some MQA. And while the sound quality in my B&W P7 was excellent, I also found it dropped MQA in the middle of the tune, where the DAC went back to PCM for a few seconds, then back to MQA again. And this was without any pause/play or other interaction from me.
This was bit-perfect playback with Roon (purple star), but might still be an issue with Roon. The tune was Kicks by Lights on her latest record which is on Tidal masters.
John, seem as You very popular user of this forum and have too many Private messages:
Response from forum engine side during attempt to send message to you:
left channel
Prominent Member
@JohnW a user on another forum has asked if there is a way to install the firmware update from a Mac. I'm wondering if there is a command line way to do this from the OSX console/terminal, or if we should just tell him to go be miserable with Windows like the rest of us.
that would've been nice. for that reason (not really S2 on it's own, but happens more often that one would like) - i installed BootCamp/Windows on my Macbook in order to have a 'windows laptop'. windows 10 eval license. it anyhow does not do anything for me except update firmware once or twice a year on something and e.g. test DAC with Windows