Carlos, Glad to hear you figured out Itunes. On Windows media player, the EQ is listed under View-Enhancements, then choose "Show enhancements" . Now you'll see the enhancements on the bottom of the screen, and to choose between them use the < > arrows in blue. There are 8 choices. Go through each one just to check the EQ, SRS WOW effects, and "Crossfading and Auto Leveling" are off. Also make sure the play speed is set to normal, it's probably set that way by default, but you never know.

BTW, as Gonk stated earlier, using the USB connection, the 2150 becomes your sound card. Try connecting some headphones to your sound card or computer while you have the 2150 connected, and you'll find there is no output. You can only have one sound card active at a time. Disconnect the 2150 and it goes back to your sound card. That's the beauty of using the 2150, no matter quality of your sound card on your computer, connect the 2150 and you have high end sound. I get some RF interference from my Sound Blaster card, so using the 2150 instead is very welcome.

Done Garth, thanks again, the equalizer was on in Windows, it is now configured as you suggested.

Garth "sounds and audio devices properties" in the control panel maintains control over volume and if you hit the advanced twice it takes you to a bass and treble screen with low and high settings, these still affect the 2150, I have set volume on max and the treble and bass in the middle and it seems to be fine, I am assuming at this point these are simply controls that do the same thing as the controls on the 2150.

Is there a problem with connecting the RR2150 to the computer through a USB hub? It seems that more often than not, I have to pull out and push in the usb cable to "wake up" Windows into seeing the UAC 3553B USB DAC as a "mixer device" in the speaker properties under "volume."

I sometimes use an Airport Express too. I have not tried the RR2150's USB connection.
Interesting that you find the AE betters the direct USB connection. Must speak to the DAC in the Airport Express. Too bad we can't make use of the AE's optical digital out with he RR2150 - everyone seems to agree that the AE's digital out really shines.
FWIW, I find I get my best 'CD Quality' sound using FLAC files. I use Play via Airfoil to the Airport Express.