1. Minimum Supply Voltage: The SSM2135 operates down to 4V, while the OPA2131 requires a minimum of 9V. This makes the SSM2135 suitable for single-supply, low-voltage systems (e.g., 5V rails), whereas the OPA2131 is restricted to higher supply voltages, limiting its use in portable or low-voltage equipment. 2. Input Offset Voltage: The SSM2135 specifies a typical offset of 200µV, compared to 1.5mV for the OPA2131. The lower offset of the SSM2135 minimizes output error in DC-coupled or precision audio circuits. The higher offset of the OPA2131 may necessitate external nulling or restricts its use to AC-coupled applications. 3. Input Bias Current: The OPA2131 features a JFET-input stage with a typical bias current of 50pA, significantly lower than the 300nA of the SSM2135. This makes the OPA2131 impose minimal loading on high-impedance signal sources (e.g., sensors, microphones), making it better suited for high-precision signal acquisition. 4. Slew Rate: The OPA2131 offers a slew rate of 10V/µs, substantially higher than the 0.9V/µs of the SSM2135. This enables the OPA2131 to handle high-frequency signals and fast transients more effectively, potentially improving audio bandwidth and fidelity. The slew rate of the SSM2135, however, is generally adequate for standard audio requirements.