I think most of the changes or "versions" have just been production run changes due to manufacturing circumstances rather than an actual "redesigned" or "improved" product.
Early DCC2 pieces have a black volume control knob, with later DCC2s having an all silver volume control knob that matches the front chassis finish. Other than that, I believe they are functionally and sonically identical.
Some CDSDs were made with an all metal transport tray and a different Philips transport than those currently in production. Apparently Philips changed transports and thus EMM had to change as well. The latest CDSDs have a plastic tray, USB port, and a more matte finish. The USB port allows for easy software upgrades.
I believe current DCC2s and CDSDs faceplates have a more matte finish as EMM had to change machine shops as well.
The above comments are only my understanding of some of the differences and may not be 100% accurate. I would try calling EMM Labs or a dealer for definitive answers.
In any event, I don't think there are any significant differences in terms of actual sound quality.
Early DCC2 pieces have a black volume control knob, with later DCC2s having an all silver volume control knob that matches the front chassis finish. Other than that, I believe they are functionally and sonically identical.
Some CDSDs were made with an all metal transport tray and a different Philips transport than those currently in production. Apparently Philips changed transports and thus EMM had to change as well. The latest CDSDs have a plastic tray, USB port, and a more matte finish. The USB port allows for easy software upgrades.
I believe current DCC2s and CDSDs faceplates have a more matte finish as EMM had to change machine shops as well.
The above comments are only my understanding of some of the differences and may not be 100% accurate. I would try calling EMM Labs or a dealer for definitive answers.
In any event, I don't think there are any significant differences in terms of actual sound quality.