1 Topic by ramraphael (edited by ramraphael 2024-11-06 02:32:54)

  • Registered: 2024-11-06
  • Posts: 3

Topic: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

Hey everyone. I'm currently enjoying my ADI-2 Pro, but wanted to switch between it and a second headphone amp for a different flavor (the amp in question is a Garage1217 Project Polaris, a solid state amp that's designed to have tube-like distortion and a higher output impedance).

I'm wondering if:
1. This is safe to do. I imagine the balanced headphone outs have a much higher level than the rear line outs.
2. If there are any notable downsides compared to using the front balanced headphone out instead of the rear line outputs (which are currently powering active speakers, so I'd need to get an XLR switch to use the same outputs).

Thank you in advance!

  • waedi
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  • Registered: 2020-12-08
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Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

At low volume setting the headphone output should work for your demand, I wouldn't crank up the voulme fully.

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
  • Registered: 2023-06-30
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Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

ramraphael wrote:

I imagine the balanced headphone outs have a much higher level than the rear line outs.

No need to imagine; it's right in the specs: +28 dBu (at high power) vs +4/+13/+19/+24 dBu on line out at full scale. At low power it's +13 dBu.

What's the input sensitivity of your amp?

Fireface UCX II + ARC USB > ADI-2 Pro FS R BE > Neumann KH 750 DSP + MA 1 > KH 120 A

4 Reply by KaiS (edited by KaiS 2024-11-06 15:36:59)

  • KaiS
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Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

I had a look into the project:
https://download1583.mediafire.com/uxyx … +specs.pdf

The schematic clearly shows:

• There’s a passive (no electronics) input control, this is unbreakable by any level ADI-2 can deliver.

• First amplification stage is a tube, again this is unbreakable by any level ADI-2 can deliver.

• There’s no balanced input, sending in balanced therefore makes no sense.


So, my recommendations:

1. Choose whatever connection scheme you like, nothing can break, but don’t expect any advantage with balanced.

2. Set whatever ADI-2 reference level and volume that’s comfortable to handle.
Typically something that gives a nice listening level with the amp’s volume about center position should be a good starting point.

KaiS's Website

  • Registered: 2024-11-06
  • Posts: 3

Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

Thank you for your help here KaiS, waedi and unplugged. Y'all not only helped answer my question, but showed me how I can look for the data (grateful RME is generous with this) and figure things out for myself if anything else comes up in the future.

Regarding balanced, although it yields no real benefit (the amplifier only has unbalanced inputs as KaiS pointed out), it's more for convenience. I have a cable from Hart Audio that connects to the dual headphone out and terminates in a mini 4-pin XLR. From there, I can either connect my headphones (also with 4-pin mini XLR cables), or eventually an RCA cable terminated in the same mini 4-pin XLR. This is just to reduce wear and tear on the headphone jacks from repeated unplugging and the ADI-2 Pro makes this really easy! Loving this device.

6 Reply by KaiS (edited by KaiS 2024-11-07 10:37:53)

  • KaiS
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Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

ramraphael wrote:

…Regarding balanced, …I have a cable from Hart Audio that connects to the dual headphone out and terminates in a mini 4-pin XLR. From there, I can either connect my headphones (also with 4-pin mini XLR cables), or eventually an RCA cable terminated in the same mini 4-pin XLR

Make sure the cable adapter chain does not short one of the hot signal legs to ground when adapting to unbalanced, a common practice.

This would short one of ADI-2‘s headphone amps - in this case you will see an according message: “Short detected …“
The amp is thoroughly protected, typically nothing will break, to be sure only slowly ramp up ADI-2’s volume.

KaiS's Website

  • Registered: 2024-11-06
  • Posts: 3

Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

KaiS wrote:

Make sure the cable adapter chain does not short one of the hot signal legs to ground when adapting to unbalanced, a common practice.

This would short one of ADI-2‘s headphone amps - in this case you will see an according message: “Short detected …“
The amp is thoroughly protected, typically nothing will break, to be sure only slowly ramp up ADI-2’s volume.


Ahh thank you for the heads up! I passed this along to the cable manufacturer to make sure it's to spec.

  • Registered: 2023-06-30
  • Posts: 161

Re: ADI-2 Pro FS : Balanced HP out as line out to external headphone amp

ramraphael wrote:
KaiS wrote:

Make sure the cable adapter chain does not short one of the hot signal legs to ground when adapting to unbalanced, a common practice.

This would short one of ADI-2‘s headphone amps - in this case you will see an according message: “Short detected …“
The amp is thoroughly protected, typically nothing will break, to be sure only slowly ramp up ADI-2’s volume.


Ahh thank you for the heads up! I passed this along to the cable manufacturer to make sure it's to spec.

There are at least two cable pinouts on the market, the so-called Mytek one and the TEAC one. You need the TEAC one (both phases of a channel are on the same TRS plug; the pinout is shown in the ADI-2 Pro's manual).

Fireface UCX II + ARC USB > ADI-2 Pro FS R BE > Neumann KH 750 DSP + MA 1 > KH 120 A