Differences between cd transports?

Um parts quality and power supply add to why one sounds better than the other, then there is the laser, plus tray loading or top clamp.  For example, a few CD transports have a separate power supply like the old Audiomeca and Metronome ones.  You can read about some of this on the Lampinzator (spelling) website or thereabouts.

Happy Listening   

There are a number of differences. And no, a DAC cannot eliminate anything coming out of the transport!!! The information extracted by the transport cannot be improved, any assertion otherwise demonstrates a gross lack of understanding of physics and mechanical engineering. That said, the quality of the actual transport mechanism can vary wildly. The Music Hall is an inexpensive player and uses lesser quality parts from start to finish. Also, isolation of the transport mechanism from transformer is a big culprit in degradation of the signal. Additionally, the quality of the coax port itself can have an effect. Build quality of the unit also impacts vibration. Lastly, all your connection points that are open allow digital distortion to enter the player. Toslink is always inferior to coax transmission. Quality of cable of course will impact. As you’ve experienced, the player/transport change impacted the sound. Remember, if the information from your source is comprised it will be down through the signal path by very definition. You can’t correct for what’s not there to begin with. Upgrade your transport if you hear a difference and you get to enjoy the music more. Remember, in the end it’s about the music! Best of luck.

tweak1-- so what was better, the Oppo 105 via coax, or the Marantz HDCD1 via coax?  I'm curious because I use my Oppo 105 via XLR's to a Hegel H360 Integrated to play SACD's and HDCD's and was thinking about trying the coax digital output to compare the sound quality.  Perhaps the Hegel DAC is better than the Oppo's, but not sure.

@dobnbav Of course that a DAC can improve things coming out of a transport in one simple way: memory buffer can entirely eliminate jitter and correct few other aspects of the signal. It cannot make up for missing data, but generally that's not the problem. And whether coax or optical is better once again entirely depends on the DAC. I'm fairly positive that a $500 Chord Mojo is not going to sound any different with either transport due to its immunity to jitter and/or signal quality (squareness of the incoming wave).

I believe @dobnbav is talking about much more than controlling jitter. As stated, the power supply, laser, etc. creates a sonic signature of the component. A poor design or low quality parts will pass this signature to the next component.