Harman Kardon AVR355 makes hiss noise in speakers

[Zaronn]

I have a Harman Kardon AVR 355 where it has started to produce a lot of buzzing sound/hiss. Especially in front speakers. Worse is the right front. There may also slightly crackling sound. Have tried to change the wiring of the speakers (left and right), and then the hiss move with it. Hiss comes regardless of the volume or the input used. Otherwise the receiver works just fine, it's just that there's been a lot of noise in it.

So, what's the most likely reason? Bad capacitors? Transistors? I've been looking inside of it, and there are no visible bad capacitors, but they could certainly be dry for that manner. What I am unsure of is what capacitors may be the cause. Are we talking about the big power capacitors? The large in the rear next to the speaker outputs? Or it may be any others that can also cause such noise?
I have a lot of soldering experience, but not very much technical amplifier experience. So I need some help here.
Someone who can recommend good quality capacitors for audio? I was thinking of Panasonic TSHA, but their hard to get (discontinued?). What could replace them? Since I have to fix the reciever im thinking of upgradring it at the same time with better capacitors (and eventually transistors if needed).
I also wonder what and how to empty the amplifier power before doing any work on it. Enough with a bulb of 220V/60W for example?

[Zaronn]

No one?

[djoffe]

If the issue is hiss...

it could be a bypass cap with dramatically reduced value across a zener diode, as the zeners are always, by nature, quite noisy.

it could be a noisy resistor somewhere toward the front of the amplifier, very likely in the emitter of a gain stage.

it could be a noisy transistor

If the issue is hum...

then likely a big filter cap in the power supply.

but from here, it's just guesses