I have really expensive, super hi-fidelity cabling. How does this affect the VMS system?

While some cables may sound better than others, or transmit more or less perfectly, almost every piece of equipment you will encounter in the balanced, pro-audio world assumes lossless and noiseless "perfect" cabling. It would be a very rare piece of equipment that calibrated itself for a certain type of cabling. Designers will measure and account for voltage drop on power rails when using long cable runs, but the balanced cabling and differential signaling method which is used in almost all professional audio reduces *signal* voltage loss to the point that it is ignored except in extreme cases. The small amount of difference in expensive, esoteric cables is noticeable to only some users, but their use will not in any way *negatively* affect anything. This is compounded by the balanced, low-impedance nature of professional audio equipment. Unbalanced, high-impedance signals like those from electric guitar pickups are affected by cabling to a *much* larger extent.