i remember that there was a little volume slider that would popup when you armed a track to record. I recently reformatted my pc, and i reinstalled the latest vegas, and no slider?
I usually don't use that slider, I usually just set it at 0dB since I use an external mixer and never pay attention to it......but you're right. I don't see the record fader anymore on V4.0d on my system either.
The input gain was presented when the hardware provided control through the Windows Mixer API. With the advent of WDM based drivers, this proved to be a meaningless slider for MOST hardware. Many hardware vendors implemented this even though there hardware did not support input gain settings. Why? To pass the Windows Hardware Compatability tests.
In the end we removed the feature as far too few devices actually supported this and all that did, had different "interpretations" of the Windows Mixer API and the results were inconsistent.