|Fluke 87V Multimeter
*Moderate DC offset, e.g. ~ 50-150mVdc, is extremely difficult to diagnose by ear. Imbalance of that nature becomes apparent only when the amplifier is approaching full output, a condition that invites other sundry (and more likely) imperfections. Those issues will normally mask the subtle evidence of moderate offset error, so aural screening—even for those who profess exceptional sensitivity—will probably prove ineffective. To be more precise, measure the DC offset.