Actually a PC is the best source for CD playback from a hard drive because it completely removes jitter. CDs are NOT really a digital format. They are an analog stream of digital data. When you go to CES you will see a lot of really high end audio companies using Ipods to drive their equipment, saying that even the worst player sounds good on their system, when in fact a digital stream to the DACs from an uncompressed audio file on the ipod is an AWESOME delivery device.
Please let's not start with this again, esp. when the fact are wrong.
1. CDs are a digital format (read the OSI layer model, if you don't understand)
2. PC does not completely remove jitter (please look into switched mode PSUs, RFI/EMI interference, interface jitter, sound card jitter measurements and audibility of jitter to begin with)
3. Uncorrelated jitter removal at full audible frequency range is a non-trivial task to accomplish cheaply (jitter attenuation is a function of the attenuation strength and passband, read Julian Dunn's Application Note #5 on jitter measurement from Audio Precision to understand why) => a high-end audio device might have that capability, a mid-level studio device (say DAC1) can do it adequately, but a general PC device has no such components/capability.
4. As to whether any of this has any bearing on hearing is probably moot, because most people can't even tell properly encoded 128kbps psychoacoustically compressed tracks apart from CD bit-perfect originals.
So, let's get back to silence, shall we.