transport sound changes in last 5 years

can someone describe the improvement in transport sound that has taken place in the last 5 years ? been out of stereo equipment for about 5 years. Was using enlightened audio T-7000 universal disk transport, was about to purchase a Wadia 20 before selling stereo.
Hmmm, I would kind of hope a transport would have no sound.
Unfortunately, I have found significant differences in the sound of various cd players used as tranports and dedicated cd transports. You would think that "bits and bytes are bits and bytes" but it doesn't seem to work that way in the audio world.
Some of my experiences are detailed in previous posts.
Best value I have found is the Parasound CBT2000. I'm sure there are better sounding ones, but they will cost a lot more.
The CEC belt drive transports are also probably pretty good.
(The Parasound is a lower priced version of the CEC's).
Unfortunately transports do have a sound although I have no real airtight technical explanation. It also seems to be somewhat dependant on the transport and DAC combination. I have heard differences even when I took the time to put the bit stream into a software program to compare the bitstreams! One possibility is the transfer of electrical noise between units. Many pieces of digital gear create huge amounts of noise out the AC lines which can be detected with a noise sniffer or a good 'scope. I use a Theta ThetaLinque with ATT optical out to break the electrical connection from my DMX digital music satellite receiver to my Sigtech. The sound improves a lot by removal of the RF and other electrical noise.