LDR Active Preamp - does it exist?

Maybe use the Burson Buffer?

http://bursonaudio.com/Burson_AB160.html

6db of gain, or about 2V. Not ideal, although it solves potential future impedance mismatch problems too.

I have three questions here regarding using of buffer:

1.) My understanding is buffer provide no gain, it is rather impedance mismatch correction device. Burson website does not indicate 6dB gain nor voltage gain. I sent them an email today to inquire about gain will let you know about that.

2.) Does Burson use LDR for volume control?

3.) What are the main differences between Burson Buffer and other buffer such as Dodd Audio.

You see, I like Goeorge's Lightspeed so much and my amp is not a good match due to low sensitivity (4V input). Another way is to add gain into my amp via mod, but that is beyond my skill level :)

CD/BluRay player is Oppo BDP-103. I dont know what are the output impedance nor voltage. I asked them the output voltage and impedance, but their answer was abit vague "designed to work with receiving equipment which is expecting an input impedance between 10K and 40K"

Amps are monoblocks Shuguang S845 MKII, which is 845 output tube.

Nguyen hi, I had a look to see in the user manual what the output of the oppo is at full volume, but it's not stated, hopefully it must be above the standard of 2v. I've been told from a guy who mods them that it is 2.5v.

Your amp says on this main page that it is <1v input sensitivity
http://shop.grantfidelity.com/Shuguang-Classic-S845MK-Tube-Power-Amplifier-pair.html
Yet when I downloaded the manual it says 4v as you say
https://shop.grantfidelity.com/files/s845mk%20manual.pdf
Your impedance matching to and from the Lightspeed is great from the Oppo's 100ohm and into the S845's 100kohm.
My question to you is do you have enough volume when the Lightspeed is almost at full up?

As "GOD" Nelson Pass and I both state:
QUOTE: "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. Nelson Pass"

Cheers George

The Burson has a 6db gain, although it isn't obvious from the literature. It also has no volume control, so you would continue to use the Lightspeed LDR.

It's called out here:

http://www.partsconnexion.com/t/Index/bur_buf160.html

And also implied by looking at the specs for maximum input voltage and maximum output voltage. Somehow it got more out than in, so it has to add it in between.

It is different than the Dodd Buffer Preamp which has no gain, does buffer, and has a volume control.