The only way you can tell the diference between 2 CDP or DVD players is to bring them home and hook it up to your system.
I once made the same mistake of auditioning various high end CDPs at various places only to conclude they all sound very much the same.
But once I managed to get them for home auditions, they do sound very diferent fom one another!
Having said that, digital sources tend to have less influence on the overall sould of a system, in the whole context if you take in to account the factor that amp to speaker to room interaction is most important.
Meaning, if you change speakers, you'll likely to hear the most diference, next followed by changing amps and lastly digital sources. In fact sometimes, changing interconnect or speaker cable will give you more diference then changing CDP.
But having said that, unless you have a very high end universal player, chances are a good mid price CD player will out perform your DVD player in terms of low level resulotion retrieval, subtle musical nouces and refinement.
The only area your DVD will have an edge over the CDP is that the DVD transport has better jitter spec., hence will require less correction at the DAC stage. But most CDPs to day uses multi disk rom drives anyway.
Hey! Where's the party?