Ignorant questions - Amps, preamps, and gain

These are questions I should have asked a long time ago, but better late than never. I’ve realized there are some terms and concepts thrown around frequently that I never really took the time to wrap my head around. Searching hasn’t yielded anything super helpful or clear to me.

My amp has a 0db gain setting, and I can easily drive my HD800 to uncomfortably loud levels with the pot at about 11. If the gain is 0db though, doesn’t that mean the amp is not amplifying the sound at all? It’s just taking what is passed from the DAC, and the volume pot is actually attenuating the level down?

If an amp has line outs to function as a preamp, calling it line out would indicate 0db gain, right? As opposed to the Lyr+, for example, which can function as a preamp, but lists low gain as 1.5DB or something like that.

Is there any concern about daisy chaining amps to use one as a pre? E.g. use a Vali as a pre to a Jot to still get the power to drive less sensitive headphones. Is the Vali is applying gain into the Jot, could that potentially cause damage to the Jot?

 

No. Line-out means it is destined for another device. Could be a sound mixer, equalizer (Schiit Loki), recorder input or an amp. Gain can be anything.

As long as your gain is low this should not be an issue(assuming you use the line-out). Nelson Pass has an amp called the F4 that is 0dB and has a lot of different configurations to power multiple speakers, often using the output of an F4 to go to a filter before going to another F4. The issue of unnecessary high gain is less the risk of blowing everything up and more that you amplify a lot of noise that you normally wouldn’t hear. This is often why a simple volume control like the Schiit Sys is all you need as a preamp

 

Line level technically refers to an output matching one of two "standards"...
https://en.wikipedia.org/wiki/Line_level
Often, but not always, the line level outputs will have very limited current capability meaning they can provide the necessary voltage swings but can only do so into a high impedance load like an amp or preamps's input which is typically 10k+ ohms. If you try to connect them to a something like an 8 ohm driver, the line level circuit can't pump out enough current to feed the load and you might either cook the chip and/or it'll clip horribly.

Sometimes, when someone says lineout it doesn't refer to the specific output levels but simply means a low-current capable output so it should only feed into a high impedance load. That would be the case of the Lyr+. Your input into the Lyr has already gone through the gain structure of the amp, the headphone jack is the main output with gobs of power. The lineouts of the Lyr have the voltage swing but not the current capacity.

Yes, the voltage in should be the voltage out. The difference is the amp can provide the necessary current, unlike the lineouts from before. 0dB gain is also typically referred to as unity gain if you ever see that working.

In a typical configuration, the source (lineout) feeds into the pot which feeds into the amp circuitry. So yes, the pot attenuates down.

In some cases the pot actually controls the gain structure of the amp, but that's a discussion for another day.

Every component has a bit of self-noise/distortion, which will get amplified by the next thing down the chain which also adds its own noise. Some people get really riled up by this, but in reality just one or two in the chain isn't that bad and some people like the flavour of it.

 

Thanks, everyone. I appreciate you taking the time to answer my questions so thoroughly. I hadn’t realized 0db gain was basically referring to voltage gain, rather than current, so that makes sense.

I have a Vali 2++ coming this week and a NOS WE396a tube sitting on my desk waiting for it. If I like this combo of a bit of tube going into the Jot R and Raal SR1-A I might look for something better or hope Schiit comes out with a balanced Saga or something.

 

Is it stupid to run a Freya in between my DAC and headamp? - Would I just open the pot all the way on the headamp and control from the Freya? I've only used preamps in 2-chan stereo separates.

 

Nah, not stupid at all. Yes, ideally you leave the pot all the way up on the headamp so it essentially takes the pot out of the circuit, but in reality I'm sometimes paranoid and always trim it down a bit depending what my gain setting on the amp is.

 

That is essential what I figured I'd be doing. If I hear noise without the preamp - I will turn it down. Pretty excited for a preamp in my system. Pretty big preamp for a Vali 2 and Piety... LOL, it's not all that will be used, but a lot of time will be with those - pretty funny. Couldn't pass up the closeout price