Bristol_Jonesey
+2
 
You've spent all that money on a computer and SONAR and now want to cheap-out on what is arguably the most important part of the entire setup.

This is worth reading again!

Agreed.
Aside from the PC itself, the audio interface is the second most critical choice for a rock-solid DAW.
The OP can get a new audio interfaces with two channels of analog I/O (decent fidelity) with a proper ASIO driver for ~$150.  
 
If the OP is investing hundreds of dollars in software (and the hours to learn/use)... it doesn't make sense to short-change the audio interface (having to live with limitations of a unit that wasn't designed for this particular purpose).

If most of the experts here actually read the OP's post, rather than just the comments about the post, it would be obvious that the OP is not asking how to build a great DAW. 
 
Bitflipper nailed it here ...
 

bitflipper
In your situation, where you just want to hear your notated compositions, you're not recording an orchestra and you're not preparing a commercial release, your internal audio interface is probably all you need.
 
There's a tendency among those of us who are pretty serious about this stuff to assume the only path is to buy the most expensive gear we can afford. Expensive interfaces, microphones, speakers. Most of us, if we suddenly came into a lot of money, would have no problem quickly blowing $100K just on stuff we've been dreaming about but arguably don't actually need.

abacab
If most of the experts here actually read the OP's post, rather than just the comments about the post, it would be obvious that the OP is not asking how to build a great DAW. 

If one expects to work efficiently/effectively:
It doesn't make sense to get a decent machine... and skimp on the next most critical component (the audio interface).
The audio interface is critical to effectively working with DAW/Scoring applications (at effective latency, sans glitches and problems).
 
Steve mentioned a nice/inexpensive option in the Audiophile 2496.
A used Audiophile 192 would be another very inexpensive solution (with balanced I/O).
You can get a new Focusrite 2i2 for ~$150.
 

Jim Roseberry
 
Steve mentioned a nice/inexpensive option in the Audiophile 2496.
A used Audiophile 192 would be another very inexpensive solution (with balanced I/O).
You can get a new Focusrite 2i2 for ~$150.

http://community.m-audio....windows10-64bit-driver
 
The Audiophile 2496 will not be updated for support with Windows 10 and has been discontinued for some time now. Some users have had success using the last available driver for Windows 7, though this is not guaranteed. You can download that driver here:

Audiophile 2496 - Windows 7 Driver

M-Audio has not made any PCI cards since this series. Our closest current equivalent is the M-Track series, which is fully supported on Windows 10. For a complete list of our Windows 10 supported products, please see our knowledge base page:

http://www.m-audio.com/kb/article/1882
 
If one is inclined to get an inexpensive modern audio interface, I agree that the $150 for a Focusrite 2i2 is probably the best investment.  But for playback only of MIDI files it is most likely a nice to have item, that you could grow into, but not an absolute necessity.  If you intend to do any audio recording, it then becomes a must have part of your rig.

bitflipper
There's a tendency among those of us who are pretty serious about this stuff to assume the only path is to buy the most expensive gear we can afford. Expensive interfaces, microphones, speakers. Most of us, if we suddenly came into a lot of money, would have no problem quickly blowing $100K just on stuff we've been dreaming about but arguably don't actually need.
 
I know this may sound like heresy. And more than a little hypocritical. But let's take an objective look at what a more sophisticated interface gets you and see how many bullet points apply to the OP...

 
It's a pleasure to read an intelligent post.