"...I know there are a lot of people who feel the CRW and DVD drivers in regular PS [CD and DVD drives in regular PCs] are just fine or even better then best dedicated audio CD transports..."
I am one such person; well not exactly; I must stipulate that:
1) I do not use the computer's CD/DVD drive and I do not transfer the data stream via optical interface. In my case files are read from a multi-drive, mirrored and striped RAID array feeding an asynchronous USB DAC. The RAID array is not physically part of the computer that accesses the data and it is configured to accommodate multiple symultaneous read requests; each drive has a 64MB buffer (I know I know; the demands in reading music files are not high and these read capabilities are over-kill). Power supplies for both the DAC and RAID array non-switching. I'm not sure this matters but the computer that accesses the data is an older Mac using Motorola processors; what might matter is that it is not used for anything else; it is loaded with the minimum of applicatoins; really only what is necessary for music playback. The library is accessed and managed using iTunes.
2) My "reference" CD player is not a CEC TLO transport + external DAC; it is an Electrocompaniet EMC I + internal DAC (the EMC I does also have an optical out for use with an external DAC; I currently do not have a DAC that will take an optical data stream).
"...What I observed was that PS [PCs] optical drives are horrible sonically, particularly if you ask them to do direct, real time play..."
I recall that you once briefly tried a Wavelength Brick (a small USB DAC that runs in "adaptive mode"; see definitions at link below); I have never heard this DAC but it has the reputation of giving good results for the money, if somewhat soft and lacking in detail when compared to Wavelength's upper end models. If I were on the same continent, I'd be willing to make the trek to Boston so that you could update the experiment by comparing a CD transport + optical against a hard drive + asynchronous USB. Maybe there's someone in the Boston area that has the equipment you could borrow (ideally a Wavelength Cosecant V3 and if not, then an Ayre QB-9)...
USB: Synchronous/Asynchronous etc:
How to short-circuit evolution: Enshrine mediocrity.