A/V Receiver vs. seperates


Forgive my ignorance, but I have only recently started to take an interest in audio. If I only want to listen to CDs, and don't really care about home theater, will I get significantly better sound if I buy a seperate amp and preamp, or should I just opt for the a/v reciever?

System:
Sony CDP-CX450 400 disc megachanger
Adcom GDA-700 DAC Converter
Acoustic Research AR1 speakers w/500 watt powered 15" subs
Onkyo TX-SV727 A/V receiver (the item to be replaced)
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$1500 would get you one of the better AV receivers, though it still wouldn't be quite the same as separates. Consider the Marantz SR-8200, for example.
I'm using the Blue Circle BC21/BC22 tube preamp/ solid state amp combo right now that you could probably find used for around $1500-1700 used. I really like this combo, it presents a very smooth, coherent and large sound. Although I have built my system primarily for acoustic instrument and vocalist playback, it handles most types of music quite well.
Seperates! That way you can mix and match or upgrade as you wish. Also the power you get from a reciever is half that of a sepreate at the same watts per.