Interconnect between h-phone amp and integrated

The basic question is: how long is too long? I would like to place my headphone amp about 15 feet from my integrated amp Will the sound be impacted? I suppose the question almost answers itself, but I'll go ahead and throw it out for opinion.
It depends on the output impedance of the integrated amp output that you are connecting to (the lower the better), on the capacitance of the interconnect cable (the lower the better), on the susceptibility of the two components to ground loop effects (which is unpredictable), and on several other variables. In other words, it's not possible to give a general answer. The most likely symptoms, if there is a problem, would be upper treble rolloff, sluggish transients, and/or hiss and noise.

-- Al
My experience (if you can do it that way) is to keep the headphone amp near your integrated, and then use a longer high quality headphone (extension) cord for your phones.