No, directed at all tubes, unless direct output coupled.The KSS OTL was direct coupled from input to output. You can do it, you just have to jump through some hoops.
I don't believe anyone has made a tube amp/preamp that is direct coupled (no caps or transformers in the signal path) from input to output, like you can with solid state.
I don't think direct coupling is a good idea for either solid state or tubes, because the timing constant of the amplifier goes lower than its power supply. At that point, its possible to modulate the supply, which in turn introduces IM distortion.
We limit the bandwidth of our amps to 1 or 2 Hz for this reason, but we do employ direct coupled inputs and outputs.