2. amps-preamps
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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
ditusa's avatar
ditusa
1,927 posts
 
@cat_doorman,
This is the preamp that includes all the desired features that you list in your post. btw, I have speakers that have efficiency >2.6%. So i understand the need for controlling gain i.e. Voltage in audio components. It is very important for sound quality. With this preamp, output voltage is adjustable from 0~35 volts. Hope this helps.


https://www.decware.com/newsite/ZTPRE.html
georgehifi's avatar
georgehifi
10,312 posts
 
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.
Only valid reason in this case for not using one, but why anyone would want an amp with 2k input impedance is wrong also, as you can’t even use tube preamps into them either! And even solid state preamps that have output coupling caps too small for that 2k impedance, as the bass rolls off if it is.

Cheers George
cat_doorman OP
237 posts
 
@georgehifi,
not sure where you're pulling 2k from. I have one amp now with 22k input impedance, and there are a some others that I'm interested in at 15k and 10k. I just don't believe in limiting my future options without reason. I also have the bad habit of leaving more than one amp connected to my pre even though I only have one amp powered at a time. Makes for an easier change, but it can present more of a challenge to a preamp. When I finally get around to experimenting with subs (that typically have class D amps) being able to handle multiple outputs simultaneously with a combined impedance under 10k might become more important. My arbitrary maximum of 500ohms would allow 10:1 ratio with two 10k loads in parallel. 


georgehifi's avatar
georgehifi
10,312 posts
 
@georgehifi,
not sure where you're pulling 2k from.



Just citing the worst of which Class-D's input impedance can be.
Cheers George
wrm57
1,070 posts
 

List of desired features:
<6dB gain
<500 ohm output impedance
tubed output
at least 2 sets of outputs
balanced in/out optional
The LTA MicroZOTL preamp appears to check all your boxes. Looks like you can drop the gain by 10db, from 10-12db down to 0-2db.  No balanced output, though.

https://www.lineartubeaudio.com/products/microzotl-preamplifier


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