Yes. Two preamps, the Messenger (single-ended) and the Atma-Sphere (fully balanced and differential) have direct-coupled outputs.
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Sure. There is a patent on the process, which is very similar to the Atma-Sphere power amps. The Patent Office supported 23 claims in the patent, which allows for a very simple method of creating a balanced DC coupled output. The output uses a circuit called a Circlotron, which has two power supplies which conduct in opposite directions through the load, the net result being- nothing.
A DC servo detects any residual voltage at the output, and applies a correction to the tubes driving the outputs. The correction voltage is heavily filtered to prevent audio from being part of the voltage- it only responds to DC.
The resulting output section of the preamp has bandwidth from DC to about 500KHz, which is much more effective than using a coupling capacitor. It also has a low output impedance, so it can drive a 600 ohm line and, in the case of the MP-1, 32 ohm headphones.