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OK, I try not to get too caught up in audiophile madness, crazy tweaks, or esoteric gear. I try to walk a balanced line between well-built, good-sounding gear and the law of diminishing returns. In other words, I'm not looking to start a revolution or stray too far outside the box; I have the tried-and-true things that sound good to me, and that's pretty much good enough.


That being said, let me ask you this: in my Office 2-channel system, I bounce back and forth between decent Integrateds and decent separates. However, as my AVS title indicates, I am 99.9% discless and digital, so my only source is a Squeezebox Duet into an external DAC. In my situation what does a Pre-Amp in the signal-path really get me? I guess my question, and this might be the ridiculous part, is...what does a Pre really do for you other than volume control and source switching (excluding a phono section)?


Well in the past, I've heard people talking about going out of CD players with volume controls, directly into Power Amps and describe the results as "magical"; to me, that's audiophile-speak, but I have to imagine it means something good...lol. Like I said, I'm no purist kook, but I can certainly get behind the argument that, in general, less is more; as in fewer steps in the signal path.


I've never tried it myself, I guess because I never felt the analog section from a mid-price CD player was "good" enough to go directly to the Power Amp, but I don't feel that way about the signal coming directly out of my DAC. And since the Duet has volume control, there's no reason it shouldn't work. I guess the real answer is to try it for myself, and trust my ears...and I will...but obviously it'll be impossible to really do a true a/b; so I was just wondering if my fellow AVS audio enthusiasts had some thoughts?


CD
 

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Quote:
Originally Posted by CDLehner /forum/post/18204051


However, as my AVS title indicates, I am 99.9% discless and digital, so my only source is a Squeezebox Duet into an external DAC. In my situation what does a Pre-Amp in the signal-path really get me? I guess my question, and this might be the ridiculous part, is...what does a Pre really do for you other than volume control and source switching (excluding a phono section)?

Nothing ... just some gain and ability to switch inputs as you said. if you're doing nothing but computer based audio as I am, just run your DAC into the amp and use the volume control on the Squeezebox. If your amp has plenty of juice that it doesn't need the gain, no need to put a pre into the chain.


I personally run from my laptop to an Empirical Audio Off-Ramp 3, into my DAC, and then into the amp - a heavily modded ICE 1000ASP based amp, so plenty of juice. And the results are simply stunning at times. The Off-Ramp took things up in a BIG way from my already excellent, Bolder modded Squeezebox 3. The only downside is it needs USB input, no wireless streaming.
 

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The preamp adds the possibility to add noise or change the signal in an unwanted way. However many serious high end guys believe that a preamp improves the sound because much source equipment does not have enough gain to successfully drive high end power amps to their full dynamic capabilities. Second there is often an impedence mismatch between the output of source equipment and what the power amplifier likes to see that is fixed with a preamp. These problems are made worse if you want to use long cables.


Also, you have to be sure the cd or dac output is using an analog volume control rather than using dither to adjust the volume in the digital domain. Dither will mean that you are not getting a bit perfect digital signal out at anything but 100% volume and above.


I believe these things to be true in the very high end equipment but in the mid fi range these things may or may not be discernible. You should try and see if you can hear any differences. I'd worry about these things in my main rig. I wouldn't give these things much consideration in my office system.
 

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Second there is often an impedence mismatch between the output of source equipment and what the power amplifier likes to see that is fixed with a preamp.

Nobody has matched I/O impedances since the 60's, not even pro equipment.

Preamps don't solve this anyway....it's not a problem.

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you have to be sure the cd or dac output is using an analog volume control rather than using dither to adjust the volume in the digital domain

Dither is used to adjust volume now? Are you just making this up?
 

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I used to be in the passive preamp camp. Switchbox, top of the line ALPS pot. Done. My preamp even had the interconnects soldered to the switches and pot to eliminate all the extra connectors, layout and crosstalk issues in preamps. I included a timed output mute through a multi-contact relay. Sorry I ever sold that one.


But, and I do not have a good explanation, I recently built a little test circuit for op-amps, mostly for headphone listening. (similar to MCoy ). As my office receiver had just given up the ghost, I used it temporary as my switch/volume control from my CD to a modified MENG tube amp, and later to a Hafler 160. I was quite surprised. It sounded cleaner. ( both amps have attenuators) This does not make sense to me as the CD does have a low impedance driver output. The distortion of the preamp is below what I can measure, less than .003 of any kind. Correctly compensated, battery driven. Too many projects to peruse this further. No explanation, just experience from someone like the OP, likes to find the corner of the diminishing returns curve. Best bang for the buck. Adding an active stage should degrade to some extent unless it is compensating for some loading problem I can't find.


Note, a lot of "intigrated" amps do not have any preamp in the line level inputs. Just the switches and pots. Even my new one, when the tone is bypassed, it is actually passive. So is my Rotel.
 
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