My recommendations were based on an actual audio interface being present.
ASIO4ALL is freeware that essentially wraps around WDM drivers to simulate ASIO, but it can be problematic depending on memory and horsepower of your system.
A dedicated audio interface has circuitry that performs the fairly processing-intensive task of analog/digital conversion (in addition to providing inputs and outputs and usually mic pre-amps and such). By moving the task of all of that conversion, it frees up your CPU for other things. Using a dedicated audio interface can make a WORLD of difference with improved audio quality - less dropouts, etc.
Using ASIO4ALL means that your CPU is still responsible for doing all of that conversion - it's just presented to your system using ASIO. This can lead to distorted sound and dropouts, which sounds like what you are experiencing.
I am no expert on getting things to sound decent when using ASIO4ALL - there are others that use it successfully for that, and there are those for which it just does not do the trick on their systems. There are some folks in the forum who can hopefully assist in getting ASIO4ALL to sound OK for you.
My recommendation is that you consider buying at least a basic dedicated audio interface for use with Sonar. ASIO4ALL is potentially not going to give you good results. Since you are using Windows 8, you MUST do some homework when you are shopping for an audio interface, as not all of them have drivers that work in Windows 8. Generally, cost for an audio interface goes up quite a bit, depending on the number and quality of inputs/outputs, pre-amps and converters (digital/analog). If you do not need many inputs and outputs, you can look for one of the more basic (and less expensive) interfaces.
Bob Bone