A microelectronic assembly may include microelectronic devices arranged in a stack and having device contacts exposed at respective front surfaces. Signal conductors having substantial portions extending above the front surface of the respective microelectronic devices connect the device contacts with signal contacts of an underlying interconnection element. A rear surface of a microelectronic device of the stack overlying an adjacent microelectronic device of the stack is spaced a predetermined distance above and extends at least generally parallel to the substantial portions of the signal conductors connected to the adjacent device, such that a desired impedance may be achieved for the signal conductors connected to the adjacent device.