What can I do to upgrade my system? Thanks


My current system right now is used for movies and music hooked up from my computer via optical cable from sound card built in to my motherboard. I listen to all genres of music and all different quality files from 256-lossless
I would say its 75% music and 25% movies on this system.

I was hoping someone could help me out with upgrading. What would be the cheapest upgrade that would give me noticeable gains in sound quality.

Here's my current system

Surround Front - Monitor Audio Silver Rx1's
Front Center - Monitor Audio BX centre
Rear Surround - Definitive Technology ProMonitor 800
Sub - Sony sa-wm250
Reciever/AMP - Denon AVR - 3805

My budget for upgrading is $400

I posted this on another forum and someone suggested I invest in a DAC(HRT music streamer pro) which started a debate in if a DAC would do anything since my Denon has a built in one. I figured this forum could help me out a little better. Also if a DAC wouldn't be my best option please let me know.
Thanks in advance
128x128bayvillian516
sorry . thought you had a seperate dac and looked again and saw you have a denon reciever with internal dac.
You could do a lot worse than using an HRT MusicStreamer or MusicStreamer2 USB DAC. Since the + series came out, the first series can be had used for a very good price. Take USB out from the 'puter, use a basic usb cable and the output from the MusicStreamer to analog inputs of your receiver. And maybe some used DH Labs T-14 speaker cables or Blue Jean cables or older model higher end stuff or Paul Speltz Anti-cables. You could do this for under $200.00.
I ended up getting
hrt music streamer 2
-belkin gold usb
-audioquest sidewinder rca's
I also decided to upgrade my speaker wires from the home depot extension cord to anti cable speaker wire.

All for just under $300

thanks for the help guys
Good choices, all. Let us know how it sounds when you get it all put together.
I thought that cbw723's suggestion to look at a USB to SPDIF converter was the best overall thought. The Hiface is excellent and, for only $150 I got good results from a Pop Pulse. Changing those speaker cables is also well advised.