Jim Lesurf wrote:


I don't know the design, but if the ltp is bipolars, consider the
resistances though which each device gets its bias current.

**There are four BJTs, 2xNPN and 2xPNP in complimentary differential mode.

In theory, Hfe matching of all four results in no input bias current at all.

In reality, 1uA or 10mV across 10kohm is easy to achieve and so eliminate the offset trim pot. But Rotel have not matched the resistor values nor matched the four device's Hfes.



.... Phil