Pre-amp worthwhile?? Denon AVR-4311 with B&W 703's


I am very happy with my system (Denon AVR-4311 with B&W 703's). I have built my own sub and sub pre-amp which I think sounds great too. I also have two rear speakers (DynAudio Image 3's) because I like the 5.1 sound for movies, but mainly I love to listen to high quality music of all persuassions.

Question:

I keep reading about pre-amps and how they can really improve the sound quality. Firstly, if so what pre-amp would you recommend I try considering my current setup and secondly, how can a pre-amp improve the sound?
uoaou

uoaou
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 I must say that I am extremely happy with the audio quality achieved through my Denon AVR and B&W speakers. It sounds amazing, truly fantastic in every way,"

Good for you to be so happy, thrilled, and satisfied why are you seeking any advise, recommendations, or consultation if you are so happy with the equipment that you have now.
Good question, I guess I find it difficult to understand technically how such recommendations (pre-amp, separates etc) can improve the sound of my system but am open to trying something new.
I believe your Denon receiver retailed for around $2100.00 so this isn’t your typical big box store low-end receiver.  Also, if it sounds right it must be right.

Some people are audio snobs and hear “receiver” or “AVR” and think it can’t produce good sound.  If it sounds great to you don’t change a thing!