Thats what it sounds like. Could also be dodgy RCA leads. We have seen a few Jaycar amps here at work for repair. Some with dud capacitors and some with dry joints on the PCB. In most cases they aren't worth repair seeing as they aren't a particularly good amp in comparison to what else you can get for a few more dollars (No offence). We generally just replace them with Alpine amps since they start at $199 these days and are a hell of a lot more reliable.