Input sensitivity matching

Ideally, should signals be matched to the input sensitivity of the device they’re fed into?
Is there any disadvantage from a mismatch?

In oder to give a somehow meaningful answer it would be great to better understand what components you want to match.
Do you have a specific setup you are thinking / worried about?

Well, generally matching a DAC’s/preamp’s output voltage to an amplifier’s input sensitivity.
There was an article on Stereophile where a senior engineer from Gryphon Audio basically stated you don’t need a preamplifier if your DAC feeds the amplifier with what it’s “expecting” to receive and that in the preamp the article focused on, there’s a “unity gain” feature that makes sure there’s no mismatch.

I’m not worried about my active monitor setup because the DAC feeds them exactly +4dBu to their set input sensitivity of +4dBu.
However, when I’m using the same DAC with my passive setup via single-ended, how can I be sure the amplifier is happy with the voltage? I guess this is standardized…?

Could someone knowledgeable please elaborate on this rather simple question?

Seriously, I trust this isn’t that hard to answer.
Is it, or is it not, ideal to match voltages precisely to input sensitivities, generally? If it’s superfluous in a given situation, please tell me why.

The simple answer is yes, and yes. It all has to do with the race to 0dB. For example, the device I use, which is of current consumer grade, has an output of 0dBV or 1v @ 0dB or +3dBu. My amp is 1.55v @ 0dB which is +6dBu. Pro audio is +4dBu or 1.22v @ 0dB. Bus gain structure for sensitivity is really pretty critical so everyone reaches 0dB with the same bus structure voltages. Many Pro amps have these settings on the rear to accommodate this. Since mine did not, I had to drop input resistor from 220ohm to 150ohm to properly achieve 0dBV at the input of the amp to match the preamp when everyone was @ 0dB.

1 Like

Excuse me, could you elaborate… “yes, and yes” to what question?

Arenith, yes, and yes to your OP

How would I go about measuring my amplifier’s input sensitivity? (If undoable with a multimeter, I guess I should ask the manufacturer?)

1 Like

Arenith, it would be very rare to not see a manufacturer of any amplifier, to not provide sensitivity in it’s specs. It could be presented in dBV, dBu or vRMS. You can drive a signal until the amp reaches it’s advertised output voltage at no load for 0dB, to determine the input voltage required to drive it there (vRMS) and get a pretty good idea, but that depends on input load. Most consumer stuff these days at line level are 0dBV or 1v @ 0dB, or +3dBu.

Okay. I wonder why +3dBu, though, since line level is exactly +4dBu?

Same manufacturer on the DAC/preamp and amp?

Yes, same manufacturer for the DAC and amp.
The DAC outputs 1.7V for single-ended and 3.4V for balanced.

Line level is whatever the manufacturer designs for, whether 0dBu, (0.775vRMS) +3dBu, (1vRMS) +4dBu, (most pro audio, and 1.22vRMS) or even +6dBu, (1.55vRMS) which when my amp was made in the early 80’s was popular. The real issue is what voltages it was designed for. Again, most consumer audio @ 0dB is 0dBV or +3dBu at line level, and most Pro stuff, +4dBu.

1 Like

I would contact the manufacturer…

Is 1.7V for single-ended and 3.4V for balanced equal to the “Pro” standard? Isn’t it?
Sorry if this a stupid question, I’m tired.

Preamp output voltage is not sensitivity. Sensitivity is a characteristic of an audio input. What is it rated for, and that is the other component I eluded to, which is load. Many preamps can reach over +20dBu in output, you have to know what’s it reference at 0dB.

Yes, what I meant is… If my DAC has the mentioned output voltages “pro standard”, I could assume my amp from the same manufacturer has matching “pro standard” input sensitivity?

Maybe so, maybe no. You would think same manufacturer, same model lines, same sensitivity. However, my equipment for example, is same manufacturer, however, 30 years apart in age, and certainly far apart on sensitivity, which is why it had to be addressed. Never hurts to check. The one rule everyone has to play by to properly set bus gain structure, is everyone has to adhere to 0dB as the reference point.


Good thing I asked about this, thanks for your informative answers.
I think people in this hobby should be more aware of the importance of this.
(People, PLEASE address your input sensitivities before even considering cable lifters, haha)