C.d player with built in Pre amps i.e Wadia

Volume control is via the analog outs of the cdp, not the digital out. In any event, I have the Opus 21 and, in my system, I strongly prefer using a separate preamp. However, this is a personal preference thing and largely system dependent, I suppose. You will only know what's best in your system by trying it both ways.

I use the Resolution Audio CD55. It has a variable analog output and I am hooked. I still use a preamp but my preamp doesn't have remote volume so I use the built in volume control on the CD player. I liked it so much I bought a second unit and have one in both systems. Bought both on Audiogon. Their is a fixed output available via a DIN type connector as well. I have compared my player to two of my friends well reviewed Marantz CD players and I feel the Resolution Audio player slightly outperformed both models overall. FYI - the owner/designer of Resolution Audio is a great guy and he makes truly innovative products. I have no ties with them in any way - just saying I like their stuff.

Brad

Raysonic 168 is incredible, and affordable. See 6moons review.

I bought one, but had no intention to use the variable out. I found it so good, I sold a $3K preamp!

you will have a hard time equaling the Pass X01 preamp from just a cd player itself. It will be close and may be better in many regards, but in terms of dynamics and control the preamp cannot be matched. I have owned the Opus 21 basic and with GNSC. GNSC brings it closer, but still not 100% there. The newer wadias I have not heard, would be curious how the 581 stacks up direct?