Cable advice

Power cables are something else and I would think that a full loom is probably not a good idea. All the power cables I have behave very differently from one electronic to another; they're all used where they sound best and swapping them around makes everything fall apart. So no, when it comes to power cables a full loom is not advisable in my opinion.

It's almost impossible to answer that question; it depends mostly on the cables and the synergy with the system. I have some cables that have a rather strong "flavor" to them; for example one that softens / warms up the sound. If I use just one between the preamp an the active crossover, it adds just enough warmth and depth; if I use it everywhere, it becomes too much, softening the top end and making the sound a bit slow and lacking dynamics. But some cables are close to perfection, if such thing exists, very transparent and neutral; with great electronics (which I don't have) it would probably make sense to use a full loom. I suspect the better the cable / the better the electronics, the more it makes sense to use a full loom of the same cable. In my case I need to play with cables to obtain the right balance.

I'm currently ordering some bulk cable that seems to be exceptional according to some friends of mine, and I will build a full loom because I wanna hear the cable in isolation; but it's impossible to know in advance if I will keep a full loom or if I'll have to mix it with my other cables. 

Also it depends on the architecture of the system. I can use a certain interconnect between DAC and preamp, then another between preamp and active crossover; but between active crossover and amplifiers I use the same cables everywhere. I wouldn't use a certain cable on the low-pass amp and a different one on the high-pass. Same for speaker cables: I always use the same on the high pass and on the low pass. I find that using different cables for different frequency bands damages the coherency of the sound. Because characteristics of a cable include not only tonal color but also energy and speed.