Are Line 6 Amps Bad?

I recently bought the RP250 multi effects pedal from Digitech and tried to hook it up with my Line 6 Spider II 30Watt amp, as per Digitech's instructions. All I can say is that the tone I got was far from being anywhere similar to the one produced on Digitech's site. In fact, after setting the Line 6 amp on the Clean Channel, turning every EQ setting to 0 and gradually increasing both the amp's and the fx pedal's volumes to a playing-without the neighbors calling the cops-level, I discovered that there was an inherent delay caused by the Spider's clean channel. And shortly after playing each note, the sound quickly faded. I tried the pedal board on my practice amp a Marshall MS-2C and was amazed to find out that there was nothing wrong with the RP250. Does anyone know a way around this problem?
After using the Spider amp for the past 2 years I would hate to think that I made a bad choice worth 260 Euros.

topic title edit by Kris