sampling sound quality

Before asking my question let me describe my set up:

portable turntable to sp303 to 2000xl.

While sampling, I have noticed the quality of my sound is better when I only use one connexion (so let's say using only the red right cable) instead of plugging both... any ideas why?

because every single cannel has its own noise and using two cables You mix two "noises". it increases total amount of noise.

You must have very noisy setup. Normally it shouldn't be any difference with one or two cables used...

wrong cable

peace

thanks for the replies.
I've tried with another vinyl & that seems to be ok now. Weird.