Local Feedback Buffers
The local feedback buffer has no global feedback loop, relying instead on degenerative feedback at each active device's output to keep the output in line with input voltage. Yes, this is the same mechanism used in a cathode follower, which keeps both its output distortion low and its output impedance low. (Solid-state devices offer the added advantage of allowing a symmetrical topology not possible with tubes, as there is no P-channel version of a triode.)
Whereas the global feedback buffer is usually run in lean Class-AB mode, in order to reduce power consumption, the local feedback buffer is usually run in beefy Class-A mode, as the higher currents both enhance the linearity and extend the frequency bandwidth.
IC examples of both types are readily found in the National Semiconductors catalog. The LH4004, LH4006, LM102 and LM310 are of the global feedback type and the LH0002, LH0033, LH0066, and LH4001 are of the local feedback type. (Linear Technology also makes some excellent buffers.) Examining the schematics for these buffers is a good source for gaining insight into the designing of a buffer, as the schematics are often reduced to idealized versions that are much clearer than their actual implementation.
MJ Stereo Technic
The wonderful Japanese audio magazine, MJ Stereo Technic also known as Audio Technology MJ, has for the last two decades run articles that featured high-power buffer circuits. Usually, the circuits look like they are just the last half of a conventional amplifier, but a few have been more interesting. The aim of these buffers is to provide no gain, but sufficient current gain to drive loudspeakers.
Surely, the logic is compelling: tubes cleanly provide voltage gain, but are current limited; solid-state devices provide huge current gains, but are not as linear at voltage amplification. (A gross oversimplification, but essentially correct.) So why not use each only for its best use? In other words, why not have a hybrid system?