interconnect ?

I have been involved in audio for about five years and have a question that has been really hard for me to answer. Where do people think you should have your best inconnects. I know some will say they should be all the some but some of us do not have the luxury to afford all of the best.

Is it better to put the better interconnect between the pre amp to amp...or would it be better from the source to pre.

I am currently running an older audio research d-60 amp, adcom gsa 700 pre processor, sony dvp s7000 source. Cables to play with are mit 330 plus ( 1m length , and mit t2 (2m legnth)

I have switched it over dozens of times and can easily say the sounds are different, but I have a really hard time deciding which sound is better. Wondering if anyone can help.