RPi + Allo Boss DAC + Relay Attenuator + Volt+ Amp

Hi everyone, @allo.com,

I currently use a RPi + Allo Digione into a Chord Hugo for headphone listening on a set of Sennheiser HD800. I’m very happy with this setup.

I want to create a new zone to run a set of floor standing Fostex full-range drivers in the bedroom. Power handling is 30W, but they are extremely efficient - maybe 95dB/W@1m - to give you an idea of their sensitivity, for the last couple of months I’ve been running them at low volume directly out of the ~1W output of the Hugo, which works surprisingly well. One thing I love about this setup is that the Hugo’s low noise floor makes noise inaudible during quiet passages.

However, I don’t really want to leave my best DAC tied up in a secondary system, driving a load it wasn’t really designed for. I was thinking of creating a permanent setup to drive these speakers using another RPi I have lying around, and buying the Allo Boss DAC, 10k Relay Attenuator and Volt+ Amp.

I have a few questions for people that have experience with a setup like this.

I’m guessing that not all of the HATs will stack electrically through the pins? However, I’d guess they should be OK to be stacked mechanically using appropriate standoffs - I’ll just have to connect the output from the Relay Attenuator to the Volt+ Amp with RCA cables?

One assembled, will the relay attenuator be controllable directly from Roon? Is setup automatic with the rest of the Allo drivers or is there a specific driver that will be needed?

How low is the noise from the Volt+ amp during quiet passages or when music is not playing? I realise this is a bit of a “how long is a piece of string” question. I’m more worried about the noise when I’m not playing anything, so if there is a way to remotely switch off the power amp via software that would be OK, too.

Finally, is there any power saving enabled on the Volt+ amp? Or is power usage from a Class D chip amp so low when no audio signal is being passed that it can be left running 24/7?



Hi everyone, @allo.com,

Ideally, I’m looking for the self noise from the Volt+ to be about as quiet as this thread :smiley:

If there’s a chance of just one question from my initial post being answered, I’d really like to know if the Allo Relay Attenuator 10k will work with the volume control within Roon?

From the documentation I can see that it works with Volumio, and that it works over I2S. I suppose all I am asking is whether there’s driver support for Roon volume control and how you’d go about setting it up.



Hi @Cameron_Fletcher - just wondering whether you have got some of your questions answered in some other ways?

I am also considering getting the Boss and Volt Plus combo and have similar questions:
1/ can the combo be left on 24/7? or is there some sort of auto-off feature?
2/ would the Allo dual power supply be compatible?
3/ anyone has rough dimensions of the acrylic cases for Boss player (with RPI), Volt+ Attenuator, and Dual power supply? Just trying to see how big these three cases would be… This is perhaps more for @allo.com

Seems a bit quiet this thread yes…

Hi @Clement_Chang,

No, I never received any reply to this question from @allo.com, @ALLO_audio_boards, or @rahulkc_s here, nor via the support form / contact email on their website. Which is weird, because they responded quickly and extremely professionally to another question about the static build up issue on my DigiOne.

As a result, I haven’t yet ordered the Boss, Relay Attenuator and Volt Plus combo and for the moment my Fostex full-range speakers sit silent and unused. If you end up trialling the combination, please let me know how it goes!



Okay thanks @Cameron_Fletcher. I have submitted an inquiry to Allo. Let’s see what happens… Really trying to get to the bottom of things quickly… :-/

Hi ,

sorry seems we mised this

No Relay attenuator will not work since it needs some specific software to control it.

  1. Yes
  2. Yes
  3. I will try to find the info

In my test setup , I am unable to hear anything. (noise from Volt+)

sorry for the total lack of reply on this.
Not sure how this one slipped through for so long.

Let me gather some info and get back at you

Many thanks @allo.com for confirming. One step closer to set up whole house audio!

If you could let me know the dimensions of the cases that would help calculate space required…


VOLT+ with stepped attenuator case size is 23cm x 14cm

thank you

Thanks Andre @ALLO_audio_boards - could I have the dimensions for the other two as well please? The case for Boss + RPI and the one for the dual voltage power supply.

Although I start to feel that three cases will get a bit cramped when on show. Are there real differences between Volt and Volt+ in practice? Understand that there is the capacitance multiplier component that’s in the latter but not in the former, would the dual voltage power supply give clean input anyway? Just trying to see if can get away with two boxes therefore a smaller footprint…

Thanks a lot in advance!

hope this helps.
will also add to site

Yes it absolutely does - thanks a lot Andre @ALLO_audio_boards.

Re the difference between Volt and Volt+ in presence of the dual power supply, is it perhaps a question more for Johan @allo.com?

Almost there thanks a lot all!

volt has no capacitance multiplier
volt+ does
volt+ & dual LLC will give the best results.

Thanks a lot Andre @ALLO_audio_boards.

I might get both for different places - a little space challenged in some places!

OK great.
let me know how it goes.

Thanks a lot for the replies @ALLO_audio_boards and @allo.com! And sorry for my delayed response, it was out of a lack of time rather than a lack of interest.

With all the information provided I’ve ended up splurging and ordered the Boss DAC with Isolator, the Volt+ with Stepped Attenuator, the Dual LLC PSU … and on top of all of that I also picked up the Relay Attenuator and a couple of LED Rainbow LED matrices just to muck around with (robotics, programming and diy are hobbies of mine). I partly went with this configuration for the EndPoint + DAC + Amp because my electronics setups rarely stay constant, and the various parts I’ve ordered seem to me to form the most flexible arrangement of standalone items if I decide in future, for instance, to move the Raspberry Pi + Boss DAC to drive a headphone system and separate out the amplifier to power some old speakers in the garage.

I’m going to see what kind of workaround I can come up with to drive the Relay Attenuator in my system. If I can’t code something that lets me drive it from Roon directly then I’m sure I can still code something to control it from the same phone the Roon UI is running on.

I’m half thinking I might even end up milling a custom case to hold the various components and physically isolate radiation from noisy components like the SBC to the more sensitive components. If I ever get around to it I’ll share photos of the build process and finished product!

Thanks again for your response!