LDR Active Preamp - does it exist?

I think I will keep the Lightspeed - sorry Steve SCM. Burson buffer sounds like a good idea. The cost is around $700 which is not cheap for what it is but if it is truly solve the high voltage input issue with my amp, that may be worth it.

I looked a bit deeper and learn that Decware offers two buffers and one of those "ZSTAGE" model is adjustable output voltage using single ended triode gain stage. It can adjust from 0 to 5 V :)

http://www.decware.com/newsite/zstage.html

Consider that my amp input is 4V, it seems that it dials to between 4V to 5V would be ideal for my amps. If everything else being equal, SET gain stage is more of my liking than solid stage base Burson.

Have anyone using the ZSTAGE buffer before?

You would want to use the ZStage between your source and the Lightspeed. If your source is 2V you can use the buffer to add another 2 or 3V to the signal. Then use the Lightspeed to attenuate.

The idea of such a device that adds voltage to the signal is not unheard of. We actually make one using all passive parts and it also has a built in attenuator.

This would be better, only use the first half it has 4 x gain, change the NE5534 for a better OPA627. It has 100k input impedance and 100ohm output impedance, put it after the Lightspeed. (Forget about the back stage with the NE5532) This would be far better than the ZStage.

http://www.ebay.com/itm/HI-FI-STEREO-NE5534-NE5532-CLASS-AA-OUTPUT-STAGE-LINE-LEVEL-PREAMPLIFIER-/261127345717?pt=US_Home_Audio_Amplifiers_Preamps&hash=item3ccc671635

Cheers George

And there's this one also,even better, already has a OPA627 and gain can be changed 7 or 2 And it has a discrete match fet output stage, I would omit R1 as the output of the Lightspeed will take it's place.

http://www.ebay.com/itm/OPA627-K170-J74-2SK170-2SJ74-Audio-preamp-DIY-KIT-/320840215695?pt=US_Amplifier_Parts_Components&hash=item4ab3912c8f

Cheers George

Burson Buffer is $550, not $700.

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

I have not much to say about the Decware. At the risk of being impolite, when people talk about buffers, Burson usually comes up first. I'd go with the more well known manufacturer in this case.