Gain into my preamp from DAC

Thanks for the nice words, Mesch.

As an FYI, a commonly seen example of a preamp (or integrated amp or power amp) having a single-ended internal signal path while providing 6 db of additional gain for an XLR input compared to the gain provided for an RCA input, would be a solid state design which utilizes an "op amp" ("operational amplifier") integrated circuit configured to differentially receive the balanced pair of input signals while providing a single-ended output. That kind of an input circuit can be configured to provide 6 db of gain, zero db of gain, or any other desired gain within a wide range of limits, simply by changing the value of two resistors.

Best regards,
-- Al

... I am not sure that the input portion of a single ended device can’t be configured to accept both signals from a balanced device when connected via XLR such that the 6 dB gain is enforced. This was one aspect inherent to my question, and as mentioned, I remain unsure of this....

... is it possible that the 6 dB gain can be maintained while the conversion from balanced to single ended is accomplished, as opposed to a designer wanting to maintain equal gain across inputs?

Yes, a design can certainly be implemented in that manner. Based on your findings, though, the preamp has not been designed in that manner in this particular case.

Best regards,
-- Al

Hi Mesch,

That kind of result is not unheard of, and two possible explanations occur to me:

1)The balanced input of the preamp is processed through a stage which receives the balanced pair of signals differentially, converts them to a single-ended signal, and in the process intentionally introduces a 6 db gain reduction, perhaps for the purpose of matching the gains provided for the single-ended inputs.

2)The circuit in the preamp which receives the balanced pair of signals just processes one of those two signals, in single-ended fashion, and ignores the other signal.

A means of distinguishing between those two possibilities would be to connect the RCA output of the DAC to the XLR input of the preamp using an RCA-to-XLR adapter. The adapter would route the signal on the center pin of the RCA connector to pin 2 of the XLR connector, while grounding the other signal pin of the XLR connector (pin 3).

If doing that results in the same volume as when an XLR cable is used, for a given setting of the volume control, it would point to explanation 2. If you hear essentially nothing when you do that, it would also point to explanation 2. (That result would occur if the preamp utilizes the signal on XLR pin 3 and ignores the signal on pin 2). If the volume is 6 db less than when an XLR cable is used, it would point to explanation 1.

Best regards,
-- Al