Low gain preamp options


I’ve read lots of preamp suggestion threads and discussions on amp matching. I don’t know what percentage of people have digital only systems, but it seems like there is a missing niche for preamps.

Most DACs have at least a 2V output which exceeds the input sensitivity of most amps. So unlike a phono input there isn’t a real need for gain in most cases. The problem with a passive preamp is some amps don’t have high enough input impedance. Also a preamp allows longer cable runs (if needed). Then there’s the whole tube warmth or tone that some people are so fond of in taming perceived digital harshness.

I’ve read about lots of tube preamps, but even the low gain ones are still in the 10dB range. It would be nice to have a useful amount of volume adjustment instead of silent to too loud with just a wiggle.

The only unit that comes to mind that’s even close is a Schiit Saga+, but it seems like even mid-fi systems should be able to do better. Don’t get me wrong, I’m using one now. It’s great for $400, but at some point it’s going to become the weak link in my system (if it isn’t already). 

List of desired features:
<6dB gain 
<500 ohm output impedance
tubed output
at least 2 sets of outputs
balanced in/out optional

Anything out there that fits the bill?

cat_doorman
Not tubed, but it would be a mistake to not consider the Benchmark LA4, with user variable input sensitivity. Meets all your other requirements, and the price is right. 
You usually want to keep the volume toward the high end of its scale. you want to amplify as much as the input signal as possible, not a small portion of it.. then you’re just amplifying mostly noise.. 

You usually want to keep the volume toward the high end of its scale. you want to amplify as much as the input signal as possible, not a small portion of it.. then you’re just amplifying mostly noise..



Correct, you want to use as much as possible of the sources output, not dispose most of it to ground with the volume control, only after which to amplify it yet again (noise and all) by the active preamps output gain stage, which btw also adds even more colouration/distortions. That's why passives are the answer, in most cases.

Nelson Pass,
"We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."

Cheers George

Thanks for all the suggestions. I actually have looked into a lot of them. (I did make an effort to search before posting.) I’ll probably need to resign myself to some sort of compromise. Maybe 10-12dB isn’t too much. It seems like some of my desired features are mutually exclusive.

Because I want the option of using some low input impedance amplifiers, I don’t think a straight passive will be a good fit for me. I also like whatever tone a tube may impart and am interested in maybe getting a little more of that than the hybrid buffer of the Saga+ provides. I think a tube stage must provide more tone with gain though. This leaves adjustable gain preamps that seem to actually adjust the input attenuation rather than adjust the gain. (Still not sure on this.)

Maybe I’ll need to do more research on custom, DIY, and brush up on my electronics. If the actual gain of the tube circuit can be adjusted in conjunction with and opposite to input attenuation then there can be a neutral effect on total gain while listening for what combination gives the best tone or presence (or whatever magic it is that I like about tubes). Once that is adjusted a separate volume control and source selector could be added. I can’t be the first person to want something like this. Maybe it just isn’t worth the trouble.

Anyone recommend a good book on audio tube circuit design? The few EE classes I took years ago only covered the basics in solid state.
look at the rogue audio RH 5 linestage headphone amp.  
front panel adjustable gain toggles of 3, 12 and 16db.  
sounds transparent and very dynamic.  love the sound.
https://www.stereophile.com/content/rogue-audio-rh-5-preamplifier-headphone-amplifier