Just the capacitor charging, if it sounds right just email the manufacturer to confirm its not a failure to happen
Is it under warranty? Out of warranty service from maker may be expensive and time consuming.
If not, open up the supply, you might find cheap parts inside, change all the capacitors, spray the power switches, then put an NTC in the line in circuit (and MOV Line to Neutral) to protect from power line issues.
And check the wire from source to speaker, might be picking something up, did to change the route recently?
And some wires do not have braided shielding, so they pick up induced noise.
You can put a small pair of pF capacitors, each channel in to ground, and also 400V small pF caps in the main (primary) circuit, to reduce line noise.
If not, open up the supply, you might find cheap parts inside, change all the capacitors, spray the power switches, then put an NTC in the line in circuit (and MOV Line to Neutral) to protect from power line issues.
And check the wire from source to speaker, might be picking something up, did to change the route recently?
And some wires do not have braided shielding, so they pick up induced noise.
You can put a small pair of pF capacitors, each channel in to ground, and also 400V small pF caps in the main (primary) circuit, to reduce line noise.
