I play Synthogy Ivory through SONAR X3 and every 30 seconds or so I hear a short buzzing sound especially when I play many keys at once. This is not directly specific to Synthogy Ivory as I get this also when I play wave clips but mostly notice it when playing live. Sometimes the sound degrades until all the sound becomes distorted. Resetting the audio engine cleans it up but eventually degrades again. I tried the WASAPI and the ASIO driver. The others don't work. I tried playing with the buffer sizes and sampling rates and even at conservative values the problem is till there. My PC is very powerful 4GHz 8 core CPU with 16Gig DDR3 and a fast SSD drive.
 
Some have suggested that my audio interface may be the problem. If so can I get a recommendation on one that works well with SONAR. I am looking for something with as little latency as possible focused on live play. I don't need many analog inputs because I don't record that much (one would be fine) but do need two head phone jacks with independent volume. Its also important that I can listen to other sounds generated by my computer in parallel to SONAR. Right now both WASAPI and ASIO drivers prevent all other apps from creating sound. 

That looks like a problem with the the power supply of your devices.
Maybe hum loops, you can hear all half minute the phase correction of your provider.
This is up to various long cables and poor shielding.
 

What interface are you using currently? If the issue goes away when you reset SONAR's audio engine, that certainly sounds like a driver problem as opposed to power supply, ground loops or other analog issues. Since Ivory uses disk-streaming of samples IIRC, you'll also want to make sure your disk is are managing the load okay, too. And check your DPC latency (Google dpclat and/or latencymon).
 
As far as a new interface goes, if you don't need portability or laptop compatibility, I recommend getting something that uses a PCIe bus card rather than USB or FW, preferably with MIDI port(s) also on the card (or breakout box) to further reduce total latency when playing live. The best FW interfaces seem to be capable of delivering quite low latencies, but you have to pay for it.
 
I haven't surveyed the market lately, so I really can't make a specific recommendation. I loved my E-MU 1820m in terms of performance, features and sound quality, but driver support was poor toward the end of its life and it eventually suffered a hardware failure of some sort. Nevertheless, I would have gone that way again but the new models didn't have the ADAT I/O I needed. I ended up with a MOTU 2408 PCIe audio interface but my MIDI ports are now via USB (also MOTU) and have twice the transmission time of the E-MU (7ms round-trip vs. 3.5).
 
 

You don't have a loop delay or similar in your project anywhere at all do you?
These can sometimes mislead you into initially thinking there is a problem by looping low level track noise until it builds up to audible levels.
 
 

I have a built in sound chip set (Realtek High Def Audio) that is on my ASUS motherboard. As far as latency shouldn't this be the best since the chip is right on the south bus? This is a popular chip set with motherboards so I don't know why I get what seems like driver degradation in SONAR. Everything else works great: hard core games, media players, media center, etc. Would an external sound card perform better or should I get an internal one? Which one? My main need is minimal latency and concurrent sound, SONAR and other apps at the same time. Haven't been able to achieve this.

Yes, you'd think that onboard sound would have a bus-speed advantage, but the chips they use are very rudimentary, low speed devices with equally inferior drivers that are simply not capable of running the small audio buffers needed for real-time audio processing. Latency doesn't matter with for basic playback as in games, MP3 players or recorded tracks in SONAR because you have no reference for what "Now" is (with the possible exception of how soon you hear a weapon discharge after triggering it). But when you're trying to play music on a keyboard, and the sound is coming out 50 milliseconds after you hit a key, you really notice it.
 
You can usually lower the latency with Realtek by installing ASIO4ALL (google it) and setting SONAR to ASIO driver mode. But it still won't allow you to run a small enough buffer to make real-time playing of soft synths pleasurable. 
 
Pretty much any name-brand external interface will handily outperform Realtek, and will deliver perfectly satisfactory latency for playing soft synths in real time. I just wanted to point out that a good PCIe interface will generally deliver the lowest total latency if that's what you're after.

Yes you are right, latency doesn't matter for recording but I am not using SONAR for that. I am mainly using it with Ivory II VSTI for live play and some occasional back tracks but the emphasis is on live play. It is absolutely my number one priority to have latency close to 0. I can currently achieve a latency of about 20ms which gets very disorienting during fast piano riffs when the produced sound occurs as the finger goes up instead of down. With ASIOforALL I have achieved close to 5ms which is livable but then I get sound pops and lose the multi-app ability to produce sound.
 
So to summarize, I have three problems I want to solve.
1. Bad latency
2. Intermittent pops and short buzzing bursts
3. SONAR monopolizes the sound production when using any drive with lower latency, I need other applications on this PC to simultaneously produce sound. 
 
I don't need any inputs or anything fancy on my sound interface other than an audio out. There are very few PCI solutions with modern drivers for Windows 7,8 64bit. Only one I can find so far in the $200 range is the ASUS Xonar Essence ST card. This card is not on the approved list for SONAR though so will this fix my issues or does anyone recommend something else?

If you are using this for live playback I have to say its somewhat insane to rely on an onboard realtek device. Onboard audio is prone to like DPC latency issues and subject to glitches based on CPU load. Getting reliable low latency with onboard audio is a crapshoot.
Get yourself a simple USB audio interface - there are tons of good ones available that will do solid low latency.
 

Which one do you recommend for $200 or less? Will the ASUS Xonar Essence ST do the job? And is it possible to have low latency and also prevent SONAR from taking over control over the PC sound muting all other apps?

Bort
Which one do you recommend for $200 or less? Will the ASUS Xonar Essence ST do the job? And is it possible to have low latency and also prevent SONAR from taking over control over the PC sound muting all other apps?

No, you need to get a sound card made for recording and one that has good drivers for low latency. Look into MOTU, Echo, Focusrite and RME for sound cards. I think k the only one you can get for under $200 may be one of the focusrite models, as those other sound card manufactures start at about $600 and go to $1800.
 
USB or Firewire are your options. I prefer USB as Firewire sound cards can be picky depending on your firewire chipset inside you rPC. You may need a Dice II chipset for a firewire card and many PC's do not include those.
So look into a USB card.
 
CJ