Tone1 - Hardware Volume via USB, Audio via S/PDIF


Is it possible to use the S/PDIF connection on the Tone 1 as an input, while the USB connection is used to change the volume?

Some background:
I am using Volumio (Raspberry Pi 3) with a HECATE USB interface ( connected to a Behringer DEQ2496 which sends the data to Tone 1 (powered via Pin 1 and 21). Both interfaces can be used in volumio and the volume can be changed, however using the Tone “only” as a DAC with volume control ( via MPD configuration) does not work. Also using alsamixer directly while the audio output is sent from the Hecate doesn’t have any effect.

Can somebody elaborate if this is a hardware “issue” from the Tone itself (like: only excepting volume commands via I2C when SPDIF is used) or a configuration issue on the alsamixer side?


So just to give some information for future readers:

  • I am pretty sure that my initial request is not possible, since the USB input will always override the S/PDIF input. Citation needed: I found a FAQ post in this forum, but can not recall where it is …
  • One possible solution would have been to cut some lanes on the PCB thus that only S/PDIF input will be sent to the DAC. However, this is risky since one can not tell what the program of the XMOS will act in a such a scenario (+ it is a shame to butcher the PCB!)
  • After reading Hardware volume - #128 by hoverdonkey multiple times, I came to the conclusion that I will do something similar like @occip and @ Coolheinze Which means writing a custom program for the XMOS, using their toolchain.

Wish me luck.

Good luck. Perhaps @Eric68 could offer some tips.:slightly_smiling_face:

1 Like

This can be achievable in theory. But it has a little trouble, we can control the DAC I2C via USB, and then DAC I2C can control the DAC volume.


Hi @Eric68 ,
thanks for the reply. Yeah, I assumed something like this, hence the “flash the XMOS” - route. Would it be possible that you release the initialisation parameter for the DAC, thus that I can recreate the same sound “experience” ?
Nevertheless, it will be fun!

Good luck!

I wish I had those skills. Instead, I’ve settled for settled software volume to 100% and getting up of my b!tt to turn the volume knob on the amp for proper listening sessions!