Splitting Balanced XLR from DAC to multiple headphone amplifiers?

I have a DAC going to three headphone amplifiers via a ONE Little Bear XLR selector switcher.

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I am wanting to exchange the above XLR switcher with a toggle version so I can run 1, 2 or all 3 amps simultaneously.

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Two questions:
1: Can I split the balanced XLR signal up to 3 ways and switch signals in various combinations without any issues or concern with the gear?
Is there an issue with 3 amps being linked together like this?

2: The splitter box is labelled & sold as a 3-in, 1-out but looking at the circuitry I don’t see any reason it wouldn’t also function in reverse as a 1-in, 3-out. (?). There are no components and it is just wire to wire connections.

Or does anyone have a better solution?
3-way XLR splitter cable? I can’t seem to find any such thing. Stereo XLR Distribution box?
Technically I’d like a four way split but that doesn’t seem to exist either…

Tech stuff for reference:
RME ADI2 FS DAC to-
Douk Audio ONE Little Bear MC103-Pro XLR Switcher to-
Ifi Audio Pro iCan Signature
Audio-GD Master 19 Headphone Amplifier
Monoprice Liquid Platinum
Monolith THX AAA 887 (currently connected to the RME via RCA)

TIA!

No one? :face_with_peeking_eye:

It should work.
One output should be able to feed three destination inputs simultaneously.

The opposite way is not recommended. Three outputs should not simultaneously feed one input.

3 Likes

Thanks, I’ll order one up!

Sound quality is at its optimum when a preamps output impedance matches the headphone amps input impedance. By switching 3 headphone amp inputs into a parallel network the input impedance of that network is 1/3rd of the regular input impedance of a single headphone amp. Hence you will suffer sound quality. How much SQ is sacrificed depends on the quality of the output stage. You can solve that by adding a line driver close to your DAC’s output in between the switch box.

Abacus Line Driver (German)

A Line Driver is a device that turns a voltage driven output stage in a current source driven output stage (more power) that is rather independent of input impedance of the load (parallel connected headphone amps).

Furthermore, never toggle the switches when the headphone amps are powered on. They will create spikes that might damage components and/or your headphone drivers or ears, when the headphones are also connected or on anybody’s ears.

So, it might work, but not without caveats.

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Copy that. Thanks, I’ll check it when the switcher arrives (after the Chinese New Year celebration) and look into a line driver. More XLR cables!!!

Yes XLR cables are not cheap. And maybe the XLR output stage is up to the task.

This may or may not be true. My understanding is that you want a low output impedance driving a higher input impedance.

Here is an article from Paul McGowan:

“Here’s what’s important: whatever you are trying to ask the output amplifier to drive must be at least 10 times higher in impedance and preferably 100 times or more. Why? Because you don’t want to lose any of the musical energy being sent to the receiving device and you don’t want to stress out the amplifier that’s sending the music in the first place.

So here are some practical examples. If the input impedance of your power amplifier is 10k then the output impedance of your DAC or preamp feeding it must be at least 1k and better if it’s 100 Ohms or less. If it’s 100 Ohms you’ll only lose a tiny amount of signal at the junction between the preamp and the amp – 100th of what you are sending, just for understanding sake (not entirely accurate but you get the idea).”
https://www.psaudio.com/pauls-posts/output-impedance/

That very low output impedance is the whole idea of a current source ie. line driver. So yes, Paul and you are correct.

However, only very few sources, and PS Audio sources may be a positive example, provide a low impedance current source output stage. Simply because the lower the impedance the higher the demand on component tolerance, linearity/thermal characteristic. Ie the higher the cost (bigger cooling surface ultra low resistance signal path). When the output stage is like a voltage source it has per definition a high impedance, the signal loses the least of its energy when the output impedance matches the input impedance of the load.

Regardless, lowering the input impedance of a load by connecting loads in parallel means that the load impedance gets lower and lower and you need extra power to transmit the signal. Extra power potentially means extra distortion if not done right.