I have a pioneer dvd player, and a NAD cd player. Both are hooked to the same amplifier, with the same wires, and the same interconnects (at least the same brand and lenght, same model), connected to the same speakers.
The soundstage is bigger sa NAD, the vocals are more clear, the sound is warmer, especially when paired with a 192/24 cd (most have an audiophile sticker) well basically, its a better sounding player.
The difference is not night and day, but safe to say, its pretty significant.
The higher you go up the ladder in gears (amp, speakers, wires, interconncts), the more you can feel the difference.
Also, take into consideration the room, if the room is not treated, and a lot of echoes are produced, then whatever player you use, It will pretty much sound the same. Its gonna sound bad.
Just my 2 cents.