[ChrisE]

Hi all! Excited to join this forum which I’ve found while looking for a solution to the following curiosity:

I have recently tried to breathe some new life into a Beocenter 2300 w/ Beolab 8000 by hooking it up to a Topping DX3Pro+ DAC / Headphone pre.

I have two aux-in cables, one is 3.5mm jack to 7-pin DIN B&O Aux, the other is RCA to 7-pin DIN B&O Aux.

When I connect the 3.5mm jack to the headphone out of the Topping (Gain 6.0 dB, volume control at 0.0 dB) I get beautifully clear sound, and I can volume-control the setup through either the input device (phone streaming to Topping via BT), the DAC, or the Beocenter.

However, when I connect the RCA to Aux cable to the Topping’s stereo line out, I get barely audible sound from the Beocenter (at volumes 40+).

Here’s the question: Is this known behaviour with the Aux inputs of this generation of B&O equipment? i.e., are they better driven from a headphone out than a line-out because of the headphone out’s lower impedance? The other two options would be: faulty RCA to Aux cable (but this one is brand new), or faulty line out on the Topping (which I hope is not the case).

Thanks a lot for sharing your insights!

[Millemissen]

Some DAC’s have different setting for the output mode.

Could it be that you’d have to change settings when using either the line out or the hp output?

MM

 

[Guy]

ChrisE wrote:

However, when I connect the RCA to Aux cable to the Topping’s stereo line out, I get barely audible sound from the Beocenter (at volumes 40+).

Are you sure that the RCA to 7-pin DIN cable is wired as an input at the DIN end? (i.e to pin 3 and 5, not 1 and 4)

[ChrisE]

Thank you both for your comments!
The Topping DAC does not allow for different gain settings on the line-out, just for the headphone out which is +6.0 dB (or alternatively +19.0 dB), 5.5Vpp, Output Impedance < .01 Ohm… (according to tech specs).

Line output is 2.1Vrms @0dBFS at 20 Ohm… Not an expert about these specs; I am not an audio engineer… But my intuition suggests that the levelling between the line out of the DAC and the Aux input of the B&O is off-specs.

@Guy: Yes, I’ve checked that (at least according to the cable specs). Also I can hear some really quiet audio input on the Beolab 8000 when connecting line to aux. See the cable specs/description from AMZN attached.

[Author]

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