Did I harm my preamp by confusing input with output?

[mkko]

I was recently moving some components around and for that had to unplug everything. When plugging things back in, I accidentally connected the RCA cable from my DAC (w/ 2V output) to the RCA outputs of my preamp, not the RCA inputs. The preamp is Denafrips Athena, and it also has balanced outputs, which were correctly connected to my power amp.

I put some music on and headed to kitchen to grab a cup of coffee. At some point I realized the music was really loud, and headed back. Adjusting volume didn't help. Changing the active input didn't help either. I paused the music, turned off the preamp and after a while turned it back on. Not yet realizing what the issue was I tried if the same thing would happen again with a song that fades in gently. Sure enough it did.

I turned everything off and started to figure out what was wrong. Looking at the back of the preamp I realized what I had done. The signal that came over the RCA cable from my DAC into the RCA *output* of the Athena reflected directly to the balanced outputs. I say directly based on presumption: the sound was crips with no distortion, just really really loud.

First question that I would appreciate your thoughts on is whether I have possibly done harm to the preamp with this? Everything sounds normal after fixing the connections, but I have this doubt/fear in my head that maybe even if I didn't break something, I might have shortened the lifespan or deteriorated the quality of some delicate component by pushing a signal in the opposite direction through it. As you can probably tell, I have no education or experience in electrical engineering and realize this question might be nonsense to those that do.

Second question is related to the preamps outputs. Does what I experienced imply that the outputs are not properly isolated and that they would possibly interfere with each other if both were active at the same time? This is a much smaller concern, but was something that came up when I was researching different preamps. I asked Vinshine Audio about this and they said that "outputs of the Athena are shared, but with a few tricks DENAFRIPS does to segregate them internally via a resistor network". Somehow it seems I managed to push a signal through that resistor network :/

This is my first post here, and in case you're wondering what kind of a dumbass makes such mistake with cables no need to share it, I've been thinking about the same thing for a few days now. I would really appreciate any thoughts from folks that know more about shared output buffers than I do. Thanks.

ps. I did ask Denafrips support first, and thy promptly responded saying that if everything sounds fine, everything is probably fine. I don't doubt their answer but am just looking to understand the situation in more detail. (Also their answer sort of leaves the door open for the possibility that something *could* have broken as result)

 

[teched58]

>I did ask Denafrips support first, and thy promptly responded saying that if everything sounds fine, everything is probably fine.
What Denafrips told you is correct.

I wouldn't get yourself into a tizzy. Audio isn't brain surgery, notwithstanding the many myths you seem to have picked up from the Stereophile-adjacent press.

 

[mkko]

>I did ask Denafrips support first, and thy promptly responded saying that if everything sounds fine, everything is probably fine.
What Denafrips told you is correct.

I wouldn't get yourself into a tizzy. Audio isn't brain surgery, notwithstanding the many myths you seem to have picked up from the Stereophile-adjacent press.

Thanks for the response!

Said press provides me no clues to understand this issue in detail. Being an ignorant person on the topic it is easy to worry even if I shouldn't. Had the support tech said something along the lines of "there is zero change line level signal does any harm to any of the components" I'd sleep well at night. It's the "probably" in their response that leaves me wondering how probably, exactly.

 

[DVDdoug]

If it's still working you didn't hurt anything.

Theoretically, it's a "bad thing" to do because outputs are low impedance and they are designed to drive a higher impedance. When you connect an output-to-an-output you are creating an excess "load" and drawing excess current and components can overheat and burn-up. But there's not much energy in these low-level signals so it's usually OK. (Resistance and impedance are the "resistance to current flow".)

If you were to connect two speaker-outputs together bad things would almost certainly happen and best-case is that one or both amps would go into thermal shutdown and survive.

As a general rule you can connect inputs together, but not outputs. i.e. It's OK to sue a Y-splitter to send a signal into two amplifiers. But, it's not OK to use the same cable to "mix" two different outputs into one amplifier. Mixing requires a mixer.

It's the "probably" in their response that leaves me wondering how probably, exactly.

There is a higher probability that the signal will be attenuated or distorted while it's connected wrong and a very-low probably of permanent damage. And even lower probability of "slight damage". If the circuit is blown it will be dead or have very-bad distortion, etc.

 

[Djano]

I did the same to my DAC (E30). I went through the same fear as you did. But since nothing has changed, I guess this is OK.

 

[mkko]

If it's still working you didn't hurt anything.

Theoretically, it's a "bad thing" to do because outputs are low impedance and they are designed to drive a higher impedance. When you connect an output-to-an-output you are creating an excess "load" and drawing excess current and components can overheat and burn-up. But there's not much energy in these low-level signals so it's usually OK. (Resistance and impedance are the "resistance to current flow".)

If you were to connect two speaker-outputs together bad things would almost certainly happen and best-case is that one or both amps would go into thermal shutdown and survive.

As a general rule you can connect inputs together, but not outputs. i.e. It's OK to sue a Y-splitter to send a signal into two amplifiers. But, it's not OK to use the same cable to "mix" two different outputs into one amplifier. Mixing requires a mixer.


There is a higher probability that the signal will be attenuated or distorted while it's connected wrong and a very-low probably of permanent damage. And even lower probability of "slight damage". If the circuit is blown it will be dead or have very-bad distortion, etc.

Thank you very much for the detailed explanation. This definitely gives me peace of mind.

 

[mkko]

I did the same to my DAC (E30). I went through the same fear as you did. But since nothing has changed, I guess this is OK.

So glad to hear I am not the only person this has happened to - also happy to hear your DAC survived