Which one...?

Soix's suggestion above is great option. The new/updated DAC3.7 is really, really good.

One other thought (if you are looking for further options) is the new Cary DMC600 (or 600SE). This is an extremely impressive DAC/CD player.

http://www.caryaudio.com/products/dmc-600-digital-music-center/

Bel Canto & Cary Audio dealer disclaimer*****

If you think the CD1 is very good, why not buy something like a used DAC3 VB and use the CD1 as a transport (assuming it works as a transport)? I was able to compare the CD2 as a standalone player and then as a transport into a DAC3 VB, and the DAC was superior in almost every way -- and not by a small margin. The most notable difference was that dimensionally the soundstage expanded in every direction, and individual performers became much more palpable in occupying their own space. Tonally it just seemed neutral and very natural, neither emphasizing nor diminishing tonal properties of instruments or vocals. Just another way to go, and best of luck.

Esoteric would be my choice.

I've had the Marantz 7s1 fro a couple of years now and like it very much. Extremely musical. But one thing with both the the Marantz 11 series and now the seven, I upgraded the fuses on both players and found ti made a big difference. I would advise anyone buying the 7s1 to seriously look at upgrading the fuses. Other than that its a great player and built like tank.

Thanks guys & yes Bombaywalla I should have included that info!
I want to try a player with a superior mechanism & DAC which I suspect will offer more detail & depth over the CD-1. My current system with the CD-1-
Roksan Platinum Pre
Roksan Platinum Power
PS Audio P3
Neotech power cords-Wattgate/Furutech plugs
Tyr 2 XLR
Valhalla XLR
Townshend Audio Isolda SC
Tannoy DC10T with Townshend Audio Seismic Bars

Music is mostly progressive technical metal, math rock (these genres are vast!)
I'm a musician so really like excellent tonal presentation & volume!

I've had my Bel Canto CD-1 for awhile & although very good I want to upgrade

why do you want to upgrade? IOW, what are your goals re. the upgrade? OR, is it an upgrade just for the sake of an upgrade?

other components in your stereo?? music tastes (as already alluded to by Jmcgrogan2)?? preferred volume for listening?

Well it depends on your own personal musical tastes. I have not heard the Accuphase, but I have heard the other two. I chose the Marantz because it is smoother and more musical sounding than the Esoteric. However, if you are looking for a more resolving and revealing CDP, you may well prefer the Esoteric.

Happy hunting!!