I have been trying to record my electric dulcimer in Sonar Platinum (If you really want to know about the dulcimer see here)
 
Everything is fine until I turn on input echo to monitor what I am playing. Things then get very distorted. There is no indication of any levels clipping and you could roughly discribe the sound as "underwater". This occures with or without effects in the FX bin.
 
The direct monitoring mix on my Quad capture is set to play back so the is no direct input signal to be mixed with Sonars output.
 
With or without the input echo on I get a good clean recording so the problem must be in the way I am monitoring.
 
I can use both Guitar Rig and Amplitube in stand alone without any issues.
 

Echo Input is for monitoring THROUGH Sonar, so from the input, through the quad capture, through sonar and back out to the quad capture.  it's used to monitor with FX and softsynths and will have problems depending on your sampling rate and buffer settings. 
 
direct monitoring on the quad capture is used to monitor at the soundcard and is a completely separate entity from INPUT ECHO in Sonar.  this setting allows you to record at the same time that the output from sonar is happening at the sound card, so you can monitor at the quad capture.  if you're using direct monitoring on the quad capture, you should not be using INPUT ECHO.
 
According to the manual of the quad capture, there is a "residual noise level" when using the direct monitoring and it implies your gain should be unity with 600 ohm input impedance.  that would mean you'll have noise at anything other than optimal parameters.
 
From the manual:
Input channel fader: Unity
 

Thanks for the detailed reply. I seldom record audio but in the past it has either been a hardware synth or from a microphone. In these cases I have always used direct monitoring from the Quad Capture.
 
I was atempting to monitor through Sonar so I could hear the effect of a amp sim while playing. I assumed this was something many electric guitarists do as a matter of course. As it seems that using input echo on the Sonar audio track is problematic is their another way to acheive this?

If you want to hear the effects of GR or some other VST, use Input Echo and turn off the direct monitoring in your Quad Capture.  Be aware you might have some noticeable latency depending on your specs and settings.

The input echo'd signal that's going from the interface to Sonar, being processed and back out again will be delayed compared to the signal that's just going from the Quad Capture's input to its output. This is because DAWs take more time to process audio than the direct from in to out function of the interface. The result is you get to hear it twice, first through the interface's own direct route then from Sonar.

To hear the amp simulator processed sound first turn off direct monitoring for the relevant input in the interface. This is usually done in the software that comes with the interface. Then enable input echo in Sonar on the track(s) you are recording to. There will be a delay between playing and hearing the sound, called "latency".

So long as the latency isn't too high most people can handle the lag without a problem. This usually means getting the total round trip time through the DAW to around 10 milliseconds or less (when the lag will be about the same as standing 10 feet away from the amplifier you're playing through).

The latency can be adjusted if necessary by changing the ASIO buffer settings, but if it gets too low for the system to handle then the audio can break up, crackle or drop out altogether. There are quite a few computer tuning tweaks which can be applied to try and reduce latency, the most important one of which is usually to disable any wireless networking in Windows device manager while using Sonar (or any other DAW).

If you run into problems with latency searching this forum should come up with a lot of information, or if stuck, ask for help.

Thanks guys. Your posts suggest the way I have it set up should work.
 
Direct monitoring is turned off (on the Quad capture this is acheived by turning the direct/playback mix knob hard right), everything works normally using both Guitar Rig and Amplitube in stand alone mode. In Sonar no sound reaches the speakers until input echo is turned on. This confirms direct monitoring is off.
 
I think however the distortion is being caused, at least in part, by the direct signal and indirect signal being mixed. On further investigation I can hear an echo with a short delay. Like a slapback delay but not as clean.
 
So if direct monitoring is off on my interface where is the direct signal coming from and why don't I have the same problem using the amp sims in stand alone? 

What happens if you set up a new project with just one audio track with no sends and going straight to the master bus, add no amp emulator and no plugins at all then play the guitar through Sonar?

Does the distorted whatever-it-is happen then?

Edit - shouldn't the quad capture mix knob be fully left (counter-clockwise) to silence the inputs? It's also possible an input may be being routed to an output in the Quad Capture's own software mixer.

Thanks, I had already tried a brand new project with no FX etc. It exhibits the problem. I also tried some of the standard track templates.
 
On the Quad Capture mix knob. Hard Left = 100% playback, Hard Right = 100% direct monitor. 100% Right I get the direct clean sound as expected. 100% left, no sound until Input Echo is on.

 

 
 

Honestly, it sounds like a driver issue to me. I've had weirdness like this with my M-Audio Fast-Track Pro. Maybe try updating/reinstalling the latest driver? And does anything change when you adjust latency/buffer size?

Hm. I used to have a UA-101 which was the predecessor to the Quad Capture. Been a while since I used it but I seem to recall that some settings in the software mixer that came with it could send an input to an output even if it was set to "playback only". I'm trying to remember how that worked but I'm not certain and the unit expired a while ago so I can't plug it in to check. It might have had something to do with the driver and interface's internal loopback monitoring settings (which could be used, amongst other things, for recording the output of, say Youtube or the BBC website, into recording software.

What I do know is I've never seen Sonar itself add a delay to anything unless a delay or reverb is working.

Could I suggest trying to record unprocessed guitar into something like Audacity or even the Windows sound recorder and seeing if that does or doesn't have the same problem? It might be helpful in trying to work out whether the problem's something to do with Sonar or hardware/driver.

It's also occured to me to ask if you record into Sonar is the echo present on the recorded track? Playing damped notes with a gap between them then zooming in on the audio picture to see if there's any echo or oddity showing up there might be useful.