LDR Active Preamp - does it exist?

If you think the OPA627 is a little hard then an OP275 is for you, but I think it's a dual, there maybe a OP175 single.
As for Burson buffer in the system position, I would put it after the Lightspeed as the Lightspeed is fine with the standard output of 2v from cd it's has .01% second harmonic distortion, but when it gets over 4v into it, the second harmonic distortion rises, not bad, but enough, to start giving that typical second harmonic distortion sound that tubes give, some even like this.
Also the Burson has a lower output impedance than the Lightspeed so it can drive lower input impedance poweramps and longer interconnects.

Cheers George

Source-->Burson-->Lightspeed --> Amp

Tried both ways and settled on the above config being slightly better.

May be you prefer the sound of a little second harmonic distortion, nothing wrong with that, adds a little ease to the presentation if needed, and may cover the sound of the Burson a little, that's what tube amps do.
But if everything is spot on in the system, then the Burson after the Lightspeed will be a more precise presentation, and give warts and all, and not be kind to bad recordings, and let the sound of the Burson through as well. This could be a good or bad thing, I'm not sure how the Burson sounds, but anything active has a sound signature of it's own.

Cheers George

George - to your understanding, is a battery significantly improve sonic quality over wallwart to power Lightspeed?

Thank you George, you nailed it. That's exactly how I would describe the difference between having the Burson before LDA or after, except I couldn't describe it well as you.

BTW, I purchased an empty Burson case to house the LDA and they look great together as a matching pair. The empty Burson case was just about a perfect fit for the LDA to fit inside. The Burson folks are very nice. Typical Aussie's.