Pre-amp to receiver?

If I play a CD , and connect  a  Denon  CD player OUT to Dynaco PAT 5 preamp IN , and then the preamp OUT  to a CD IN of an Optimus STAV 3000 receiver( which has no connector in back to separate the receiver's preamp and amp) I  seem to be able to use both the Dynaco tone controls and also the Optimus tone controls to effect sound through speakers.

The questions are two...1) since the Optimus has its own quality of preamp, which of course does not rise to level of Dynaco PAS 5,  will this mean that no matter what quality signal the Dynaco is inputting into the Optimus receiver CD input, that signal will  degraded to however  the Optimus receiver preamp would handle a direct CD IN signal without the Dynaco, or will it be improved  isomewhat due to an added emphacis on some frequencies or the ability to discern those frequencies or whatever by the Dynaco?

2) if the above is audio anathema,  as i suspect, is there a correct way to bypass the receiver's preamp (with a receiver that does not have the two small metal connectors in the back to disengage its  preamp from amp) and insert the Dynaco 5 as the tone controls?

I googled this question but the net seemed to provide confusing or inadequate response.

Thanks to anyone who takes the time to read and/or respond..