Longer XLR Runs

In over 25 years of this High-end Hobby I have never used or experimented with an interconnect run of over one meter in length. I have a want not need to move my source/preamp about 3.5 - 4 meters from my amp. I would use XLRs for obvious reasons (gain,etc) but my question is how much will this affect the dynamics or sonics in general? I certainly don't want to jeopardized those for any reason. I could do longer speaker runs which I have done in the past with good results, but I want my amp in the middle so that's not an option. Any thoughts or facts would be appreciated. Thanks Chris.