What Souncard or Rig Interface you use?

No, using a soundcard of any type only degrades your signal. To use a hardware interface & soundcard, the digital signal has to be converted to analog, passed through the interface, & converted back to digital. The D/A & A/D conversions add a small amount of distortion by their very nature. Using DAX, everything is kept in the digital realm & therefore no distortion due to the conversions. -- 73, Ray, K9DUR

George, I had issues with RF and hum until I added ground wires to my ground bus for my computers. Each piece of equipment has a short, heavy, # 8 stranded wire to a copper bar which then goes to my ground electrode just outside my shack. This is in addition to the 3 wire cords which provide a safety ground. It did work for me.     73, Jim

@George

I suggest you read my paper on How to Build a Quiet Station...

Here’s a link to PowerPoint “How to Build a Quiet Station V2.pptx” in my Dropbox for a talk I gave at the San Diego DX ca club in July 2014.

https://www.dropbox.com/s/d2yturid60n...

Here’s a link to PDF “How to Build a Quiet Station V2.PDF” in my Dropbox:

https://www.dropbox.com/s/kffp92esffo...

Remember you can never had too many Ferrites on your station.

DEFINITELY DO NOT USE a SOUND CARD or EXTERNAL RIG INTERFACE

They only make things WORSE.

James, I couldn't have said it better ;-)
If HF is not where it belongs, string heavy ground wires!
All my equipment is grounded and I use different power supplies for the TRX
and my inferfaces and TNC's, when operating PACTOR or using my TS2000.
I have never had problems with HF and my equipment, although I regularly
blasted external equipment, like mice and lamps, until I used a lot of ferrite beads on them :-)
73, Alex - DH2ID

Alex, I think it comes from my 42 years in medical x-ray, building and fixing cardiac cath labs. We needed to keep equipment current leakage down in and around the patient for 1.5 meters. We could get it down to about 5 or 6 microamps if you were very careful.  I have never needed ferrite beads in any of my stations and I have run some serious power ( currently run 1200 watts). Also, a truly balanced antenna system really helps.      73, Jim

QED

To Quote Ray:

"using a soundcard of any type only degrades your signal. To use a hardware interface & soundcard, the digital signal has to be converted to analog, passed through the interface, & converted back to digital. The D/A & A/D conversions add a small amount of distortion by their very nature. Using DAX, everything is kept in the digital realm & therefore no distortion due to the conversions."

So you are already doing your best with DAX and your 6000 Series.. a Sound Card will only make it worse

FYI - I have consistently  seen decodes of -29 with my 6700.  

A couple of years ago Rob WA3IHV and I ran some tests of a Signal Link and a IC-7700 vs a 6700... the 6700 and DAX consistently would decode at least -6dB better than the Signal Link.. we did not test the Signal Link on the 6700 because of the obvious degradation of the Digital to Analog to Digital process