There should be ASIO drivers for the Presonus and line outputs to run to the speakers from the images I saw.
USB Audio Interface, 2-in/2-out, with 2 Microphone/Instrument Preamplifiers, 2 1/4" Outputs, MIDI I/O, and 1/4" Headphone Output with Studio One Artist Software - 24-bit/48kHz
http://www.sweetwater.com/store/detail/AudioBoxUSB/ I run my computer speakers (I have a RME Babyface) as well as headphones out of the unit. With the Pesonus AudioBox you have Main Outs L and R to hook up powered speakers - which most computer speakers are, as well as listen to headphones from the unit - look at the back image, as well as a MIDI connection into and out of the computer, all of handled by USB.
I fail to see why you are not hooking everything up to the Presonus AudioBox - with a 1/4" adaptor to a mini-plug (3.5mm) used for some headphones, while someheadphones include the 1/4 adaptor. A mono version if using the main outs (L and R) can be used usually bought at a electronic store - 1/4" to mini-plug mono for each channel (L and R) to hook up you speakers, if that is a stereo connection like a headphone cord, then they also have a connection adaptor for that also where you get both (L and R) 1/4" plugs to a stereo mini-plug which you then can plug in your computer speakers in a single short cord - L is usually white or grey and R is usually red on the short cord. (if you were running video that way you would have a yellow colored part of the cord too). That is all standard and probably costs maybe $5 for the entire cord, although it could cost a little more.
Then you can always plug headphones into the back of the Audiobox and also your speakers into the Audiobox, and everything is running through the Audiobox.
http://www.revouninstaller.com/revo_uninstaller_free_download.html Version 2.5.9 down on the bottom works good if you want a program just to see if you have any strangler files on your computer and check it out. Usually you can do the same thing in Windows in the Control Panel -> Programs and Features to uninstall drivers - but if you had changed drivers, are not using drivers since the sound card is out, Windows 7 keeps a copy of every driver for sound or graphics you ever had in your computer. That program may help to delete any drivers not going to be used since you took the extra sound card out.
The other way is to right click on Computer Desktop Icon and get up Properties. Get up Device Manager and Delete anything extra in Sound, Video, Game Controllers and uninstall the drivers (yes Windows still have them there perhaps) and restart your computer until Windows 7 can not find any drivers for any of the sound cards - probably just the Presonus since you may have un-install the other sound card drivers. But, that program link can also find files left over by programs that did not fully un-install (those do that, ya, know) until it is reasonable sure that you have nothing there for Windows 7 to install once you start up your computer with your AudioBox connected. (if old drivers Windows will install those until you delete them all, and do that until you restart your computer and it finds no drivers.) I just went through that with the RME Babyface I have, because RME over the last year a quarter came out with several newer versions of drivers and they did not have an un-install program before. I had old drivers - 6 to 7 of them still on the computer because Windows 7 is a pack rat with that stuff. I uninstalled them all by deleting the Babyface out of Device Manager also checking for Windows to un-install the drivers and doing that by restarting the computer several times to delete all of them.
The program listed though may find drivers that are not needed (since you removed those other sound cards) that are not attached to any device now, and perhaps find them and then delete all that stuff.
You should not need anything except the Presonus AudioBox for everything with the newest drivers from Presonus that work (which should include the ASIO drivers, the Windows drivers like the WDM/KS whatever which will give latency, or the MME drivers which also are bad. The ASIO drivers are the only ones that will account for latency and what you record and what you hear will be at the same time, and not delayed by the drivers).
Think simple, you need no other unit except the AudioBox and to me, you can run your speakers from your computer and also listen on headphones by plugging into the back of the AudioBox. I do the same thing on my Babyface except I have one more headphone jack so I run my computer speakers from that, can listen to headphones also, and also have the output jacks that I can run to other powered speakers if I want to.
If I did not and only had one output for speakers I may have to switch speakers to listen to more than one set of speakers, but I use my computer speakers usually more than anything else except the headphones.
That is about it, simple, everything through the AudioBox, set up in Sonar with the outputs and inputs from the Audiobox and every sound through the Audiobox, whether movie, game, utube, itunes, your recordings whatever.
??
To me it is that simple.