J River is one of the best samples of stable bit-perfect operation:

It works with ASIO drivers, and most ASIO drivers are bit-perfect by design.
ASIO can bypass completely the Windows sound system, the Windows volume control and mixer are out of the picture.
ASIO allows for easy automatic sample rate switching, so another limitation of the operating system is eliminated.
ASIO is very light-weight, my driver works with J River up to 8 channels at 32bit resolution and 384 kHz sampling rates.
The only area for configuration is the J River player. To have bit-perfect operation, the user must keep the setup simple and basic - no DSP processing, no up-sampling, no channel mixing, no bass processing, no software volume control.

"Fully transparent" means bitperfect. The bits from the media file delivered to the input pins of the DAC chip without any changes. It also implies that the data delivery is jitter free. Of course the DAC will introduce some jitter, but the interface, the delivery medium can and must be jitter free. This is one of the major advantages of Asynchronous USB over legacy audio interfaces like SPDIF.

George