My guess it the Dittel will want line level input, not amplified speaker input. I don't think the V7 has line level audio output. You might need some signal conditioning for starters... In order to reduce radio noise when you are concentrating on centering a thermal, you would have to turn the radio completely off, and that might turn the vario off too... You also might miss some subtle awareness cues from having the sounds come from different directions that may enhance processing the inputs. Note how good the brain is at filtering out the conversation next to you in a restaurant, so you can focus on hearing the person across from you...