By design a computer will always output a superior digital signal. Bit-perfect data is read from harddisk to memory then upsampled with much better precision. This happens in a noiseball but critically outside of any realtime clocking mechanism and no bits are mangled/lost (essence of computing). Hence no jitter occurs during data prep stage.
Last stage transfers buffered data perfectly to sound output device (connected via usb, ethernet or internal bus). This device adds a clock and generates spdif signal for dac. This task will create jitter and needs to be optimal (clean power not sourced from noiseball, very high quality clock if dac does no input buffering and/or reclocking, etc.). All transports have same challenge here.
The way I see it, traditional transports suffers more jitter. In realtime, CD spins, data is upsampled (but not as good as a computer) then fed to dac this all happens under a strict clocking regime. As noted in Altmanns website (What is Jitter?):
A simple CD player has multiple motors or actuators and associated control loops, in order to perform disc reading:
There are f.e. the spindle motor that turns the CD, the sledge motor that performs axial tracking, and actuators for focus and radial tracking.
Each of these motors / actuators will add a portion of noise to the power supply of the player and this noise will affect accurate switch timing.
So, each of the motors /actuators adds jitter to the digital audio signal and each adds a different kind of jitter (different in frequency, amplitude, waveform) and will affect audio reproduction in different ways.
Put another way, jitter is compounded by the spinning CD which induces various types of power supply jitter. (I can see why esoteric built the VRDS Neo mechanism.)
Novas Memory Player does away with spinning CDs in realtime. Playback is driven by a computer.