Hi virtualsamana!

I think it might not be the busses, but the track send levels you should be looking at...

Let's look at the track output options:

There are essentially TWO sends off each audio track: you may send a signal straight to the Master- (or any other destination such as a BUS or EFX chain)- using (First) the main output assign (to the left of the RECORD button) where the master, bus or EFX chain is assigned your track's signal, the strength of which depending on the setting of the main volume slider... or, (Second) the output from the multipurpose slider (below the main slider); when you assign this output to a bus or EFX chain, the multipurpose slider volume also has to be up (it opens at -inf. or NOTHING, right?) for anything to get to it's destination out of there, no matter if that slider's input is set to pre- or post- volume (of the main track fader). If this second output is at -inf (OFF)or so low it doesn't get 'seen' by the BUS or EFX, the pre- or post- choices you make won't make any difference, because NOTHING is getting out of there anyway.

From your post, It sounds like you need to check that the multipurpose slider is up enough for the destinations (BUS or EFX) to hear it. THEN, your pre- or post- volume (fader) choice will make a difference.

The pre- and post- selections are input switches for your multipurpose slider.

In PRE- if you cut the track's main volume all the way off, you'll still be getting a signal to and out of the multipurpose slider, because it gets its' signal before that signal passes though the main volume slider. (conversely, set to POST-, the multipurpose slider gets its' signal after it goes through the main volume slider- so the main slider will also boost or cut the secondary slider's input/output.

To sum up, With the multipurpose slider off, nothing gets sent out, no matter what is selected.
In POST- when the main volume slider's off, no signal is sent to or out of the multipurpose send.
In PRE- with the main slider off, you'll still have signal at the multipurpose slider.

The thing can get interesting, though, if you happen to assign a track's output by setting both the track's output selectors to a single destination.

If you assign the main output to BUS 'A' for example, and also assign the multipurpose slider's output to BUS 'A', then the differences you might see as you adjust the multipurpose slider up and down won't seem to be affecting the input level of BUS 'A' as much as it should; it is because the main send is already routing the signal to that input! This gave me a 'walk around the block' when first setting up a session, too. (Asa in, "Why isn't this making any difference?!")

Hope this was helpful-
Doc