It can't be that we have to use TWO separate sliders to adjust balance. Zillions of mixer application have a balance slider, so why doesn't kmix have one (any more)?

Reproducible: Always

Steps to Reproduce:
-
Actual Results:  
Balance can only be adjusted in a most clumsy way:
1. You have to split the channel first
2. You have to adjust "balance" of every channel separately. 

Expected Results:  
There should be a way of using ONE slider that can "juggle" between L and R channel.

Using the "split channels" feature to adjust balance is a total overkill IMHO. That actually doesn't qualify for the term "adjusting balance" - it's simply a kludge that imposes an additional and unnecessary burden on the user.
For a starter, he can't "play around" with the very same slider to have a 70% output on the left speaker and then _immediately_ reverse the situation by putting 70% on the right speaker (leaving 30% on the left). He currently is forced to juggle around with two sliders, which may end up in lots of clicking.

NOTE: Splitting channels, however, is not an unwise thing per se, mind you. I use it for splitting the wave channel so I can adjust volume for "poor man's" capture (e. g. off youtube) and playback volume separately. (weak source = capture to the max, so you might avoid having to amplify the audio e. g. by audacity) Just don't "abuse" it for a balance slider replacement. It will not come even remotely close to a true balance slider; hence this feature request.