If it were me I would leave the DACMagic out of the picture unless you use an optical connection, because on USB it won't do over 16/48. See the FAQ on the Cambridge Web site. (Where they say USB is inherently limited to 48KHz. It's not.)
For sonics, I think it is worth saving to go higher up the scale if you can. The Benchmark is very popular and you might like it. The Apogee Mini-DAC is actually my preference at that price, though.
Even though small upgrades are fun and teach you things, they are potentially more expensive in the long run than a single big step. If you want to squeeze more out of your CDP (which is very nice for the price), and you haven't tried tweaking it with a premium AC cord, antivibration footers, an isolation transformer and all the rest, well, consider that. After you upgrade, many tweaks can still be useful, or be resold without much loss if you buy them second hand.
For sonics, I think it is worth saving to go higher up the scale if you can. The Benchmark is very popular and you might like it. The Apogee Mini-DAC is actually my preference at that price, though.
Even though small upgrades are fun and teach you things, they are potentially more expensive in the long run than a single big step. If you want to squeeze more out of your CDP (which is very nice for the price), and you haven't tried tweaking it with a premium AC cord, antivibration footers, an isolation transformer and all the rest, well, consider that. After you upgrade, many tweaks can still be useful, or be resold without much loss if you buy them second hand.