plugging a Cdplayer to Vintage sx-880 Pioneer

do i need some attenuator because signal ouput from Cd player is higher than the tape inputs

No.

The "tape in" and "AUX" inputs are line level inputs. Just don’t try to use the phono preamp input.

Is there a reason you can not use the AUX input for the CDP?

https://s-media-cache-ak0.pinimg.com/originals/3c/41/56/3c4156464ee08bcd344360aca955ee86.jpg

i tried both Aux and monitor tape 1 or 2 i dont understand why the monitor tapes inputs sounds better to me and the aux sounds louder but too much mids a highs a little bit exagerated i read many people prefer the monitor over the aux .

Make sure the "Loudness Switch" is in the off position.

People said output of cdp are 2V and input line are 150mv and so .

I believe the "tape in" inputs and "AUX" inputs are 2v

I could not find an owners manual for the SX-880.
Here is the service manual for the SX-880.
Note the #3 Block Diagram.
http://akdatabase.org/AKview/albums/userpics/10004/Pioneer%20SX880%20Service.pdf

Let’s work through a real example to make things easier to follow (using data for my Pioneer SX-1250 receiver and Marantz CD-65SE CD player - typical of many vintage amp / modern CD player combinations) :

Input sensitivity of SX-1250 "Aux" (and "Tape") inputs : 150mV
Output voltage from CD-65SE at maximum signal level : 2000mV (2V)
So the CD player output signal is 20 * log(2000 / 150) = +22dB higher than that required for full output power from the SX-1250.

What this means is that the receiver’s full power of 160 watts will be produced with the volume control set to -22dB (referenced to maximum = 0dB). Fortunately, in common with much high-end equipment, the SX-1250 has a volume control marked in -dB, making it easy to see where this occurs.

Perhaps the most "surprising" thing to come out of this calculation is just how little the volume needs to be turned up to get full output : -22dB on the SX-1250 corresponds to somewhere between the 11 and 12 o’clock positions.

http://audiokarma.org/forums/index.php?threads/amplifier-sensitivity-decibels-and-you.58829/

More:
http://www.hi-fiworld.co.uk/amplifiers/75-amp-tests/150-sensitivity.html

http://www.decware.com/paper55.htm

https://www.vintage-radio.net/forum/showthread.php?t=101306

http://forums.stevehoffman.tv/threads/is-your-cd-player-changer-too-hot.350381/page-4

No you will not damage the SX-880 if you don’t crank up the volume control knob to high causing the amplifier to start to distort. If you turn the volume control up to high that will drive the amp into clipping, then you could fry your speakers.

If you read any of the links I provided the common thread is not to turn the volume control up too high which would overload the amplifier and cause it to distort and further increase in the volume clipping.

You can drive any amp into distortion/clipping if you crank the volume up high enough. (Depending on the connected source)

If Al, (almarg), by chance has seen your thread maybe he will take the time to chime in. Al will be able to explain in technical terms in a way the layman can easily understand.
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