The preamp is the heart of a system. It handles signals at their lowest level and hence has the greatest possibility for damageing the signal. The distortions from electronics also tend to be more noxious than those from transducers so I would suggest a new preamp, tubes perhaps to balance the adcoms literal coldness. A small investment in interconnects will also yield a fabulous improvement in this system, however it is hard to make a recommendation because we do not know what you are looking for i.e. smoother, sharper, more dynamic,etc. Good luck!
