Preamps... understanding volume...

The amp is an Odyssey Audio Stratos Extreme.
The DAC/Preamp combos I am considering...
Pro-Ject Audio Pre Box S2 Digital
Pro-Ject Audio Pre Box DS2 Digital
Topping D70
RME ADI-2
MiniDSP SHD
NAD C658
... obviously quite a range. I’d like to spend the least amount possible balancing a great DAC with remote volume control. Sub out, MQA decoding, EQ, and streaming are pluses, but not required. Since my source is the Mac Mini, I have some flexibility in software taking on those features.

Unfortunately it appears that sensitivity is not specified at the Odyssey site for any of the Stratos amplifiers. Nor is gain, which in conjunction with the maximum power ratings could be used to calculate sensitivity.

And I couldn’t find relevant specs or measurements elsewhere after doing a quick Google search. So I suggest that you contact Odyssey and ask for that information.

Regards,
-- Al

Ozzy is right. 

It may help to understand that usually the first stage the signal sees is a high impedance, fixed gain stage. For historical reasons, this gain is often way more than needed.

The volume knob comes after.

Schitt Audio Fraya or Saga would let you see if you need the passive or active preamp as it can switch between both. $299-$899 

I was typing from a bar, so couldn’t put a lot of detail. The simplest active preamps I know of are perhaps the Conrad Johnson PV10s, but they have a lot of similarities with others. The structure is something like this:

Input --> Source selector --> Fixed gain, high impedance buffer --> Volume knob --> Output


The combination of the fixed gain (+ x dB) , and volume (- y dB) loss determines the final output level relative to input.

One thing to note, while these systems are super simple, and short, they also are sensitive to the volume knob setting, like you see on figure 1 in this review:


https://www.stereophile.com/content/audio-research-reference-6-line-preamplifier-measurements


This can be improved with additional buffer stages, at the cost of more devices in the audio path.


Along with gain comes noise though, and honestly, we have too much gain in most preamps, especially tubes. We’d be better off reducing the gain, and using the volume knob closer to 12 o’clock.

Anyway, the point is, active preamps almost always have a fixed gain stage, but the output is almost always lower than that.

Best,

Erik