Typically you would start at the source, so preamp to DAC or phono. But there are no rules on where to start; ARC preamp to ARC amp may result in the most dramatic change in sonics. Start with one cable change to see you like the sonic signature.
My suggestion is to audition a few cables by contacting http://thecableco.com/
There's a 5% charge to borrow cables from their lending library, which you'll get back if you make a purchase. Try Cardas, but also audition the Purist Audio Museaus IC ($675 for 1 meter with a very realistic sound).
I've used the Cable Company many times. It's much cheaper than buying cables and reselling them. My system is more modest than yours, but I went with all Purist cables. I couldn't have done that without auditioning them first.
Keep me posted if you decide to upgrade IC's.
My suggestion is to audition a few cables by contacting http://thecableco.com/
There's a 5% charge to borrow cables from their lending library, which you'll get back if you make a purchase. Try Cardas, but also audition the Purist Audio Museaus IC ($675 for 1 meter with a very realistic sound).
I've used the Cable Company many times. It's much cheaper than buying cables and reselling them. My system is more modest than yours, but I went with all Purist cables. I couldn't have done that without auditioning them first.
Keep me posted if you decide to upgrade IC's.