Sound Blaster with Cakewalk?

+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.

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.
 
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...
 
1. Low noise, low distortion, and minimal crosstalk. These are not necessarily prerequisites for everyone, certainly not for somebody who just wants to make a composition audible. Even the noisiest, nastiest interface will not prevent you from exporting a pristine digital mix for distribution.
 
2. Multiple inputs and outputs. Not everybody needs them. Especially if you have no need for inputs of any kind, such as is the case for 100% ITB composers, and your only output requirement is to hook up speakers.
 
3. Digital inputs and outputs. Not driving digital speakers, bringing in audio from external synthesizers or digital devices? You don't need ADAT, S/PDIF or TOSLink.
 
4. A dedicated MIDI port. Yes, MIDI over classic 5-pin DIN allows for more versatile connections and in some cases less-problematic connections. But in the OP's case, all the MIDI is internal to the computer.
 
5. Bespoke drivers. Using a built-in interface might necessitate using generic high-latency drivers, whereas a well-supported pro or prosumer interface will support all the driver models. Companies like RME write their own drivers and are always working on improving them. Our OP doesn't care, and needn't care, about latency - only reliability and simplicity of use, which MME excels at. And it will always work with every Windows version.
 
6. Metering. Irrelevant to the OP, who only needs to make sure his output stays out of the red.
 
7. Better headphone amplification. Here's a potential plus the OP might care about, having enough oomph to push some headphones properly. But headphone amplifiers can be bought separately, and if the headphones are efficient enough, or aren't used at all, may not be necessary anyway.
 
8. External effects. Great if you're recording vocals so you can give the vocalist reverb in his cans, but useless to the OP. 
 
9. Mixing and routing options. Many interfaces are full-featured mixers. Mine is as capable as most mixers I've ever used, but how many of us ever change their interface routing? Muting channels is about all I do.
 
10. High sample rates. Some integrated audio interfaces are limited to 48 KHz. Although sample rate often triggers debate, we can all agree that if you are playing back only sampled instruments, there is zero benefit to upsampling them from their original sample rate. 
 
11. Miscellaneous features. Phantom power. Balanced I/O. External controls. Rack-mountable for tidiness. XLR/TRS Neutrik connectors. Not applicable to the OP.
 
These are just off the top of my head. I'm sure others can think of additional benefits of a high-end interface, but they're likely equally irrelevant to the OP.

Just for the record, I have been using the on-board Realtek audio chip in my el-cheapo Acer Aspire E-15 laptop, with the freeware ASIO4ALL drivers, and the 1/8" audio output.  This is a year old model with a Core i5 mobile processor (dual core), 4GB RAM, and a slow 5400 RPM HDD, running Windows 10 64-bit.
 
For playback only.  No audio recording.  Just to use a USB MIDI keyboard to control virtual instruments hosted in Sonar synth rack.  Can also play MIDI files mapped to VST instruments ...  the 4GB RAM seems to be the limiting factor as far as the number of VSTi instances that can be run.
 
It actually works very well!!!  No glitching, dropouts, or delays. I even get close to the same latency as my desktop DAW does with a Firewire audio interface.  I only got this laptop for mobile computing, not audio.  I already have a DAW that exceeds my needs, but was pleasantly surprised to discover I could play around with the laptop while traveling.
 
Edit: Also for the record, I tried this on-board Realtek audio configuration with Sonar and the available Windows drivers (MME, WDM, and WASAPI) instead of ASIO4ALL, and could not get usable performance.  It sounded very bad, with long delays and dropouts.  The Windows drivers sound good for me only with web streaming audio and video such as media players, YouTube, Netflix, etc.  That stuff can buffer all it needs to provide smooth playback.  But for real-time audio, no.
 
If I wanted to do more with the laptop, such as mobile recording, I would probably add a $100 USB audio interface with ASIO drivers.  Probably the Focusrite, Tascam, or Steinberg 2x2 type units would suffice for lightweight recording purposes.