The Truth is not a passive preamp, it is an active preamp with no gain.
I believe it uses an active buffer stage (one buffer on input and one on output) to provide high input impedance and low output impedance. Unity gain is probably a more accurate way to describe it. With today's source voltages, I doubt you would have any trouble driving typical amplifiers using today's sources with a unity gain device. Also, it would be much better at handling the interconnect characteristics than a passive. It does not have a remote control, display, or balanced connections.