Sim Audio W-5 matches well with most tube preamps due to its high gain, high input impedance and good voltage sensitivity. You will have a more difficult time (but not impossible) mating the X-250 with a tube preamp because of its gain and input impedance.
I use the Sim Audio W-5 and Supratek Sauvignon.
I use the Sim Audio W-5 and Supratek Sauvignon.