Devices, systems, and methods are provided for accessing the interior of the heart and performing procedures therein while the heart is beating. Connector-contact assemblies are disposed in the connector lumen and adapted to couple to terminals of the lead when the lead is received by the connector lumen. Power dissipation occurs when the subscriber lines are fed with a voltage level that is higher than necessary. The comparator circuit compares two multi-bit input values. The delay balancing engine may examine the modified model to determine whether any delays or latencies have been introduced.