Low output / just ok sound?

Just started experimenting with Hi Rez downloads. I have a few from Acoustic Sounds, HD Tracks and Sound Liason. I am using Windows 7 pro using the Asio driver setting outputting via USB to an Oppo 105D. What I have noticed is I must use what I think is a significant more amount of volume to match the levels from the cd output of the 105. The downloads sound ok but not as good as by best SACD or CD's. Other than upgrading the above equipment is there anything I can do? Is the lower output normal.Any suggestions would be appreciated.
Volume differences between sources is very common, so there may be nothing wrong. That said, make sure you disable all software volume controls. Also, to do a really good comparison, you should use the same exact album. Try ripping one of your CD's and compare that rip to the CD you made it from.
Hey Bufford.

Could you tell us more about the computer you are using, the software used to playback?

I never used a 105D. Do you know if the USB input is asynchronous or synchronous?

As Zd said, I wouldn't worry at all about differences in volume.
thanks for the replies.I understand there are differences between different sources this just seems a little extreme.
I have not listened to a ripped cd for some time but I don't think there is a difference with them.
The 105d is asynchronous and I am using JRiver. The computer is an HP probook nothing fancy. I'll have to check software volume controls, if I can figure out how! not much of a computer guy.
"I have not listened to a ripped cd for some time but I don't think there is a difference with them."

You need to try everything or you'll never fix the problem. Who knows what kind of processing was done to the downloads you bought?

Make sure that nothing in your system is using replay gain. If something is, disable it.
I have changed the volume settings in Jriver and all is well.It takes some time to learn Jriver believe me I'm not there yet.
Thanks for your input guys.
Thumb drive, .wav files or flac. I have three 32gb thumb drives with most of my music on, so much easier now. Put all of your files on a spare external harddrive should the thumb drives get corrupted. Remember to shut down the BDP-105 when swapping thumb drives, same approach as telling windows to safely eject.