good question. i had the same idea (i.e. cheap trasport/good dac) when i began shopping for my front end. i learned that basically, you're screwed with crappy stuff no matter where it is in the signal chain. a high-end dac will not compensate for a mediocre transport and vice-versa.
for a given price point, it's usually better to get a very good one-box player than less good(?) digital separates. also remember that separates will require another (digital) cable which can itself be a source of sound quality degradation (not to mention that they're often $$$$).
for a given price point, it's usually better to get a very good one-box player than less good(?) digital separates. also remember that separates will require another (digital) cable which can itself be a source of sound quality degradation (not to mention that they're often $$$$).