thanks for adding to the confusion, Kamal :lol:
But that high vol issue would be with pre-amp as well? you have turn it down before powering up the system?
You are getting confused between different input/output paths of ONE: a two channel system, and TWO: a multichannel system such as an AVR.
Most Oppo and many other DVD Players has a small pre amp built in as they are connected to a TV directly. The manufacturers assume that TVs do not have large amplifiers, and they have a preamp built in for convenience. The Oppo, for example, output 1.0V through it's composite, component, and S-Video connections. This is about 6 times the signal strength it would supply if you use it as a CD player and taken a RCA out to an integrated amp.
When you connect such a DVD Player to the CD input socket of a stereo integrated amp (as instructed by the DVD Player manual), the DVD Player will output only the specified signal strength.
This, though, is not the case in traditional audio equipment such as CD Players, TTs, etc. They have only one output.
Pre amps expect each socket to receive data with predetermined specifications - roughly 2.6mV for a MM Phono Cartridge. 0.15mV for a MC cartridge, 160mV for CDs, Tape and Aux input. The THD and SNR specifications are based upon these as well as impedance and sensitivity figures. If you do not stick to these figures, the preamp will start distorting very quickly.
Mobile players have internal amplification for headphones. These can be used to connect to an external pre/amp combination. When you do this, the best is to keep the internal amplification at a extremely low level. A pre amplifier expects it's input to come in at a particular voltage and gain. If you pump in more it will start distorting very quickly. Try this with an iPod. Using a cable (on the headphone socket), connect the iPOD to an integrated amp or you car stereo. Keep the volume of the iPOD low, and you will hear clear music. Increase the iPOD volume, and you will reach distortion very quickly even without touching the volume knob on your amp. That is why they have the iPOD docks. These extract the music at levels expected by the preamp and give you clean music.
The audio and video industry follows some standards. We must ensure we stick to those standards if we have to have clean sound and clean images.
Cheers