[sk007]

I think I read somewhere that said, the headphone output on the Headamp Pico is very clean, and could be used to feed to another amp without any SQ degradation.

I don't quite understand this. How do you amplify an already amplified signal? and have the same SQ as coming out from just one amp? I'm confused.

 

[jh4db536]

people desire the coloration/sound signature of the Pico's DAC while driving their headphones using a separate desktop amp. It's not all about amping the [Signal]. It's about driving the headphone.

the Pico's DAC does exist in a desktop form (dedicated source)

 

[tfarney]

Quote:

Originally Posted by sk007 /img/forum/go_quote.gif I think I read somewhere that said, the headphone output on the Headamp Pico is very clean, and could be used to feed to another amp without any SQ degradation. I don't quite understand this. How do you amplify an already amplified signal? and have the same SQ as coming out from just one amp? I'm confused.

Folks who want to use the Pico's DAC as a DAC into another amp justify this by saying, accurately, that all DACs have an output stage that boosts or pre-amps the signal with an op amp anyway, that this is really no different, and that the Pico's amp section is very transparent, so they are not adding any color or distortion by using it this way.

That may very well be right, but in theory, it is amping an amp, adding another gain stage (and a rather heavily amped one with a potentiometer in it) and piling on any noise, distortion or coloration in that stage. It's not generally considered a good idea.

Tim

 

[tjumper78]

i've read about several (credible and experienced) members using pico as a preamp that feeds to desktop amps, and no one had any complaints.
so thats the setup i'm definitely going to try when i get mine.

 

[Assorted]

I'm using my Pico > line-in to a speaker amp, and it sounds wonderful, much better than iPod w/ LOD.

 

[sk007]

thanks for the inputs guys, they really helped a lot. now anyone has a Pico to spare? for a good price?

 

[sk007]

one more question comes to my mind. will it be a problem for the second amp that the signal from pico is not actually at line level? isn't going to enter non-linear region fairly easily since the second amp is design to amp line level signals? I'm asking this because I am thinking about using the signal out of pico and feeding it into a speaker amp.

 

[Duggeh]

If the benefits of using a larger more capable and more powerful amp to drive the headphones, despite the imperfect nature of using an input from an amplified output on another unit are greater than the benefits of the simpler equipment chain but use of the less powerful and less capable amp then the sound can easily be better when using the Pico in this manner. Just keep the gain and output on the Pico low and use the grunt of the second amplifier to do the driving. Its somewhat like, to use a rather loose analogy which people might pull me up on, a two box system similar to Quad's "current dumping" amplifier topology. Except that the Pico isnt a low gain, class A amp.

 

[Downer]

I remember reading that Justin was using Pico as preamp/DAC in his speaker setup.

 

[jinp6301]

Quote:

Originally Posted by jh4db536 /img/forum/go_quote.gif the Pico's DAC does exist in a desktop form (dedicated source)

where? link please!

 

[holland]

I hope people realize that not all preamps are passive. Sometimes it's preferable to have an active stage for driving the line, as well as to provide a small gain to reach line level, or to provide differential to single ended conversion.

If you have discrete components for your speaker system, more than likely you have an active preamp. If you know your preamp is passive, then you know enough to not even ask the question posed by the OP.

Not all device outputs can directly drive a power amp, which may have a higher input impedence than the device likes (adding different non-linearities vs. an active stage). Applying that component "topology" to a headphone preamp -> amp is no different.

There's also the matter of converting a differential signal to single ended for the run of the mill headphone amplifier. Also, impedence mismatches, etc. There's usually some sort of compensation one way or another, either transformer coupled or an active stage.

Regarding line level. Define line level. AFAIK, it can vary from about 1Vrms to about 8Vrms. So, what are you getting at?

Can you get a cleaner signal? Sure. Those that usually require one active stage only can or rather should be able to determine this audibly. If they can't then they are just doing it because "someone told me to".

 

[tfarney]

Quote:

If they can't then they are just doing it because "someone told me to".

Which is, of course, why many things are done many audiophiles. I seriously doubt that the Pico, used this way, produces distortion that anyone can really hear, but it is another gain stage. Technically bad mojo.

I also seriously doubt that most users can really hear a significant difference between the Pico used this way and most audiophile DACs, but try telling that to the guy who spent a couple grand on a DAC.

Tim

 

[22906]

The thing is you don't have to worry about the signal being too loud from the Pico, because you can always tune it the point where you hear clipping, and then reduce it. You will probably never have to go past low gain, full volume to satisfy any amplifiers input level requirement.

 

[tfarney]

Quote:

Originally Posted by m3_arun /img/forum/go_quote.gif The thing is you don't have to worry about the signal being too loud from the Pico, because you can always tune it the point where you hear clipping, and then reduce it. You will probably never have to go past low gain, full volume to satisfy any amplifiers input level requirement.

I get that, but clipping isn't the issue. Theoretically, everything you put in the signal chain can introduce noise and distortion. This is why audiophile component builders go to so much trouble to design equipment that is simple - with the shortest possible wires or traces and the fewest possible number of parts, and it's why they go to the trouble and often considerable expense of using audiophile-grade parts - resistors, capacitors, potentiometers, wire, etc. This is why, for example, audiophile-grade components rarely even have bass and treble controls.

When you put the Pico's amp in the signal chain unnecessarily, you put a lot of parts in the stream and you amplify them. Bad audiophile juju. Can you hear it? I doubt I could. But I'm sort of an unapologetic undiophile, or audiophool, depending on your POV. if you're using your Pico as a DAC between your source and your home amp, and at the same time you're upgrading the caps in your amp or staring longingly at a maxed-out Woo, or investing in high-end interconnects or replacement cable for your phones, you're a bit confused. And conflicted. And at war with yourownself. But carry on.

On the other hand, if you're just plugging the thing in, inaudible traces of noise and distortion be damned, and enjoying the music, I'm right there with you.

Tim

 

[holland]

Quote:

Originally Posted by tfarney /img/forum/go_quote.gif but try telling that to the guy who spent a couple grand on a DAC.

Wrong analogy.

Plug that DAC *into a preamplifier* and that is what you now have. The Pico, when used before an amp, is a DAC + *preamplifier* in one case. It even includes a volume knob, like a preamplifier.