“The buffered version of the LDR preamps will be a separate product probably referred to as a LDR Buffered Preamp to distinguish them from our LDR Passive Preamps. ”
Sounds interesting, but what is the difference in sound quality between the LDR buffered preamp and the LDR passive preamp?
The answer is a very unsatisfying "it depends" but that's the right answer.
Let's say you have a source (for ex. a DAC) with a robust output stage (as good as this buffer! ) feeding into a passive preamp which serves as a volume voltage divider of that signal. Adding a buffer is unlikely to improve the sonics since you already have a powerful source.
On the other hand, if your source has a so-so output stage connected to passive preamp then the sound quality may benefit from a buffer that can deliver a more powerful signal. By powerful I don't mean louder (higher voltage) but a voltage signal with plenty of current supply such that there's little or no voltage droop regardless of the signal (big bass slams for instance).
Not all sources are created equal. In my view many manufacturers of DACs, CD transports, Phono stages, tuners etc. assume that there will be a nice robust preamp downstream to stiffen up the audio signal so why "overdesign" the output stage of the source. I think this is why there's such a wide variation in peoples' experience with passive preamps. Adding in a buffer usually overcomes the shortcomings of a lesser source. Or you can just blame it on the passive preamp.
I recommend a buffer vs. a full blown active preamp because in 95+% of cases you don't need the gain stage of a typical active preamp. A truly simple and effective buffer gets the job done with the least number of components and shortest signal path which more often than not results in a better sounding system with less noise.
Sure, there are also potential impedance bridging issues if the effective impedance of the passive || amp is too low but I've found that to be far less common a problem than all the attention it gets.
In short, if you're using a passive attenuator, weak sources benefits from a buffer, strong sources don't need a buffer.