So the title pretty much sums it up. I built a new computer around February (general specs are in my signature), which was an upgrade from an older laptop running XP, but still I get stutters and glitches during playback and recording in Sonar X2a. My guess is that it could be my relatively inexpensive interface, as that's what my sound is coming through during playback and recording. I even get these stutters with something as basic as a track for a mixtape where the instrumental is one single .wav file before even recording any audio.
 
A few notes:

• Project sampling rate is 44,100kHz
• Driver Mode: ASIO         Dithering: Triangular
• 'Use multiprocessing engine' is ticked
• Render bit depth is 32bit
• I've kept task manager open during playback and my CPU usage is in the single digits, my RAM usage is generally under 25% (Often less) and Disk usage is in single digits

 
So far I've tried:

• Disconnecting from the internet and closing all possible background applications.
• Increasing buffer in the ASIO panel to its maximum
• Going to Preferences>Audio>Sync and Caching>File System and increasing the the Playback I/O buffer size to as much as 1024 KB (currently set back down to 512KB)
• Tried ticking '64 bit double precision engine'
• Bipassing all FX
• Updated ASIO4ALL driver to newest version

Does anyone know of anything else I can try? Or if my playback issues are likely a result of the interface? Actually I'll also go and test through onboard sound (sound through my motherboard).

The interface does not have a factory ASIO driver? Using ASIO4ALL is not a good idea. You might try uninstalling ASIO4ALL and use whatever driver comes with the interface. SONAR does not require ASIO, it should work with whatever native driver the Alesis iO2 Express uses.

I agree.  If you are forced to use ASIO4ALL, your interface is most likely the culprit.  Have you visited Alexis site to look for most current drivers?

I am a bit confused about why Alessis suggests you use ASIO4all on a class compliant (presumably WDM) driver. The ability to use an ASIO settings box does not seem to justify the potential problems. 
 
The most likely cause of problems you are describing given that there is no indication that you are overloading your system capabilities is a DPC latency issue, a less likely cause would be driver conflicts by having two audio devices installed at once. Webcams, USB microphones, video cards with audio capabilities can all load audio drivers that can sometimes be a problem.
 
The first thing to do would be look in device manager and disable any audio drivers that are not for your audio interface. If that fails to help get into your bios and disable any on board sound devices there. While you are at it disable any onboard wireless networking device at the BIOS level. After that it gets interesting. Download and learn to use latencymon. http://www.resplendence.com/latencymon
 

Yeah there's no factory drivers for this little interface (unlike my last one, a much larger Alesis Multimix). I just tried playing audio without the interface, through my motherboard's onboard audio: far less stutters though still some on occasion. To do this I had to switch the Driver Mode in preferences to 'MME (32bit)'. I then tried playback with the same driver mode using the interface, still less stutters than originally, but a bit more than playback without the interface.

I'll take a look at other audio drivers too. I haven't installed many peripherals, although I did have a video card and sound card (Creative) installed, they were both a bit older from another PC. I don't really game and my interface handles the audio for me, so I took both out. Tried to uninstall most of their software, but maybe I'll double check for anything lingering.

One more update, I uninstalled ASIO4ALL completely, now just using the MME (32bit) drivers. Played some other projects, I think it's about the same amount of stutter as I got with ASIO4ALL since even that didn't stutter all the time. Think I'll deal with this for now, the MME driver will actually share the audio drivers (while ASIO didn't) if I minimize Sonar so I can browse the web or play other multimedia, and it gives me higher volume for the direct sound of my mic coming through my headphones, so that makes things marginally easier for me.

If anyone else has any ideas, they'd be much appreciated. I've been wanting to get another interface, thinking the one of Focusrite Saffires since I've heard good things about their preamps.
 
Btw, here's another related question. With the Alesis IO2 Express, it has a fader knob to balance between USB sound (playback from DAW or the PC) and direct sound (actual mic or other line ins). This is really important for me because I use it to control how much of myself I hear when recording, as Sonar's 'Echo Input' has a lot of latency and throws me off.
 
If I later get an interface like the Saffire that doesn't have this balance, what other options do I have for changing levels of playback VS input? And should the 'Echo Input' have latency or is that possibly due to my interface as well?

ASIO4ALL is not a true driver. It is a wrapper which presents the existing driver as an ASIO driver. It was written for software which only worked with ASIO.

Every interface I have used has a way to blend the direct monitor with DAW playback. Although with a low latency interface and a modern machine, I don't use direct monitoring as often as XP days.

scook
Every interface I have used has a way to blend the direct monitor with DAW playback. Although with a low latency interface and a modern machine, I don't use direct monitoring as often as XP days.

I was looking at the Saffire Pro 14, didn't have a knob on it, but apparently it uses software for direct monitoring, so that won't be a problem. I'll research a bit about the Saffires' latency before I buy anything, but still If you're not doing direct monitoring, what in Sonar do you use to monitor your inputs and how do you balance them?

Most of the time, latency is low enough to monitor through the DAW. The audio interface still supplies the audio out for monitoring, the tracks being recorded have "echo on" enabled in SONAR.