older CD transport vs newer ones.

Couldn’t disagree with you more, maybe try better transports. I was using a Cambridge CXC ,which is a fairly good transport for the money, with my Mojo Audio EVO DAC . However, I took the advice of Ben at Mojo Audio and upgraded my transport. I decided on a SimAudio 260DT which provided an obvious improvement in SQ..

ejlif, I would suggest upgrading, maybe checkout the Forum thread on the new Project transport, seems a number of members are very high on it.

Sounds great, wait for it to die.

Meanwhile, be ready to order a replacement.

My Experiences

1. Onkyo DX-7500, dual matched burr brown processors, 18 bit, 8x oversampling 352.8 kHz, all the mechanical isolation, optical tricks, etc. they could think of

http://www.hifi-classic.net/review/onkyo-dx-7500-430.html

Damn drawer started misbehaving, still played, still sounded terrific.

2. Niece was throwing away a Sony 5 disc carousel Video Player, DVP-NC80V ( lost remote). I could use if for picnics, parties, why not. Single processor, 24 bit, 192 kHz

Damn thing sounded as good as the Onkyo. Everyone agreed.

3. Let's try an Oppo BDP-105. dual ESS Sabre DACs, 24 bit/192 kHz.

Damn thing didn't sound any better than the single processor Sony Carousel. Sold it, lost $204. 

+1 @facten .
Transports are better designed to output a low-jitter stream than a CDP.
It may be all 0s and 1s, but it’s also the timing and purity of the signal; no distortion to affect the rise time and shape of the square wave. This tech is built into a transport. You can hear this.

older CD transport vs newer ones

Stay away from slot loaders, they are just cheap rubbish.
Older Philips/Sony tray loaders were great, but!!!! some lasers are very expensive or impossible to find 
Cheers George   

I added a fairly inexpensive CD transport to my DCS Rossini DAC/Clock and am shocked how much better it sounds spinning a disc vs streaming it.

https://forum.audiogon.com/posts/2237249