Vocals have no gain despite hot input.

In any case I would check where the output of your tracks is going and the gain/fader levels of whatever buss they are going through as well. 

To further diagnose, try inserting a Synth like Session Drummer 3 and play a loop through it. Is it also really quiet?

If your soundcard has its own mixer like my FireFace 800 be sure to check that too!

Jim has the waveform changed in the drawing in the track from what you saw as you were recording?

Alarm bells ringing....Offset mode?

Check you haven't a some point put it into offset mode and reduced the faders or perhaps just the master buss fader. Press 'O' to toggle, you can tell you're in offset by the + sign beside the volume pan etc.

Any changes you make will stick but not show when you exit offset mode.

'Trim' is referred to as "gain" within X1. It's available on the track header view. (Make sure your widget settings are on 'All')

Offset exists to change the overall setting of a track with envelopes on it, although in X1 it's now easier to use the envelope itself.

If you have a good strong signal recorded there must be something pulling it down. Check your track output is going straight to your master buss. If it goes somewhere else check the fader on that buss and also to see if there's some sort of processing happening on that buss.

When you play the project back what maximum peak level do you see? You can see that info in the CV toward the bottom of the fader. It'll continue to display that after playback stops.

I can assure you if this was/is an X1 issue this forum would be close to explosion with rage.

Don't worry about envelopes at this stage, you haven't got one active if you can change the fader. I'm now thinking that perhaps you have the prochannel turned on on that track and the compressor is bringing the level down. Check that isn't the issue.

When you say "weak signal" you are presumably referring to the level of the volume as opposed to the level that the track was recorded at. Those are two different issues. Are you sure the recorded levels are healthy.

That may help but if everything is already going through one & only one buss the problem must be on the track somewhere.

In the TV you get the PC to the fore by first making sure the inspector is visible. Press 'I'. Then if the PC isn't already visible press 'Ctrl + I' to show/hide it.

At the very top of the PC there is an on/off button that shows blue when the PC is active. Try turning that off. That will bypass all the individual modules even though their individual on/off state doesn't change. From the "sounding compressed as hell" it sounds to me like you have one of the PC compressors active and squeezing the level down without the make up gain adjustment.

Another thing just worth checking is the actual level recorded. The wave form can "Look as hot as hell" but it is possible to scale the view of it, so it could appear to look "hot" but in fact be quite low.

Maximise the track by double clicking in a free area of the TV header and then have a look at the scale on the track header/clip pane divider to get a better idea of actual levels.

SONAR does not know if the audio is vocal or drums or a truck driving by. Audio is audio.

That's a very good point.....