I have owned all of the following CD players w/built-in volume and prefer them in this order (favorite at top of list, least favorite at bottom)
Resolution Audio Opus 21
Quad 99 CDP
Cary CD-308
Theta Miles (superior balanced version)
The Opus 21 is excellent, but I needed to decrease my audio expenditure, so I sold it.
The Quad 99 CDP is an excellent value at $1499 list. I paid $825 used for mine and it is one of my best audio investments EVER!
Enjoy,
TIC