I'm very tempted to buy the 7520 DAC but I'd like to get some input first.

I have a Squeezebox 3 connected to a Cambridge Azur 640A, speakers are B&W685 on good stands.
Cables are Tara Labs Spectrum Helix 8 and Spectrum 3a.
Files are mostly FLAC.

This setup sounds ok but I'm missing high end details, soundstage and more.
Maybe I have to high expectations from a cheap system? (I used to be a hi-fi enthusiast with Apogee Scintillas (1ohms) and such.)

Could someone offer any input on how much a DAC like the 7520 could improve the sound from my system?
I guess the analogue out on the SB3 is pretty good for the price, but...

I also have Beyerdynamic DT770 Pro 80, should/could the 7520 be modified to match these?