Do I really need a preamp?

As long as you don't need analog inputs or anything like DSP or room correction, you should be able to do this. I know that when I direct connected my Oppo BDP-93 to my power amp it sounded very good indeed...

The Ncore NC1200 Class D amps were the first I heard that sounded anywhere close to as good through a passive preamp as through an active or buffered preamp. With the D-Sonic you may meet your goals without a preamp. If you already own the preamp I would definitely try it both ways.
BTW, if your source is a computer, you can do room correction through your player, probably as a plug-in.

I really do as it sounds much better if you have a great preamp as i do.

Hi Robcentola,
Welcome to this site. You may not be aware that audiogon has a vast archive section. I suggest you type in active preamp vs passive and/or active preamp ve direct source connection. Rob , this topic has been discussed hundreds of times (or close to it) and you will get the same answers from both sides (you'll see). It will depend on the quality the given preamp and other system components. It will also depend on what type of sound you're seeking. There's no one best answer, you'll just have to actually "listen" and decide. Some active preamps are superb and will be an improvement and some will degrade your sound compared to direct connection. It just depends.
Good luck,