I've got a motorhome, and i've just got a dvd head unit, it's one of those
cheapo chinese ones (arkon) but the price was right for what i wanted,

One annoyance, when ever the volume is turned on (i.e. off mute) i get a
loud hiss in the speakers, this happens on all modes, dvd/cd playback,
radio, aux in.

even with nothing connected to the unit except power and the speakers, i get
the hiss, so it's not anything i've connected to it (which is only the audio
from the sky box)

I can make the hiss louder by turning up the trebble (think it's called that
on this unit, other one to bass makes no differance if i have the loud
function on or off, it has 3 preset equalisor settings, and the hiss changes
in volume slightly when they are cycled through.

I guess this wouldent be a problem in the standard car setup where you need
the volume up loud to overcome the engine noise, road noise etc, but in the
motorhome especialy at night ,we can easily hear the sound with the volume
on level 2, and of course the hiss is almost louder than the sound then.

Is there such a thing as a hiss reduction unit?? i'm using the unit's
internal amp, and want to keep it like that, that's why i bought a dvd head
unit in the first place, the speakers in the TV are at the back and are
tiny, and were far too quiet due to the TV being built into a cabinet, so
the dvd head unit got me the amplified speakers on the front i wanted, but
now i have this damn hissing.

I have tried different power supplies, the unit has it's own circuit
directly off the batteries, i tried it off the TV's regulator which ensures
exactly 12.8 volts gets out no matter what the input voltage is, and removes
all spikes, ripples and hash on the incoming power, still got the hiss.

Anyone got any suggestions to how i can reduce this hiss, i can get it
bearable by turning the trebble right down to minus 8, but then the sound is
weird as you'd expect.