Set the stage. I set up two synths to record intro. Draw fades and everything. Playback loud and clear. Go to record it to audio. Solo tracks. Hit record. About 1/4 of the volume as playback when recording. Not just that, the patches don't seem to be responding the same way as they do on playback. CRANK VOLUME (although this shouldn't be an issue, it plays back fine.) When I monitor it is loud. When I hit record, strange behavior soft volume. These are hardware synths, so I shouldn't be getting any volume issues( like I've routed the audio through multiple busses and hence the volume change. Nothing changes except the record button. I keep the mixer settings identical (using a Mackie 1202).Needless to say, the recorded audio tracks are soft too. But that isn't even the issue. When I hit record and transport starts moving, I get big drop off. Any ideas what I might be missing?

Oh midi buffers 128. process using 540 ms buffers. Sound card (Komplete audio 6) at 24 bit 44.1 using 128 sample buffers.

When you are monitoring your hardware synths, are you monitoring though your interface or direct to headphones/speakers? I ask because it sounds like your interface is recording at lower levels than your monitors. You should adjust the monitor levels and the levels being sent to your interface so that what you hear in your monitors better approximates what you expect to hear after recording and playback.
 
Regards,
Dan

Tried both. I'm only using headphones because I took the outputs from the mixer (that feed the powered monitors) and plugged them into the interface. I have monitored from both the mixer phones out and the interface phones out. I can see the interface and mixer being different levels, that's almost to be expected, but monitoring direct from the mixer before recording and while recording yield very different results. That makes no sense to me whatsoever. Both synths are plugged into the mixer, the only variable is pressing the record button (the big one up top in the transport section.) even when it is cued(like when you would typically set volume) , but not yet recording it's loud I am no noob to this, that's why I'm so confounded. I am wondering if I have something checked that would offset the velocity of the synths or the audio level when recording. I can't remember having level troubles when recording the info into sonar, but maybe I had no reference point.From the synths point of view, it's just playing back normally, why would it drop in volume? Even normalising it after the fact raises the volume, but it sounds weird like it isn't following the automation envelope. (which is just velocity). Next step, monitor directly from the synths themselves. While I doubt it will make a difference, I can eliminate something. Also, I'm going to try soloing just one at a time. There may be some midi channel weirdness that I have overlooked, but I would think that would manifest itself during playback as well.

Kind of sounds like your interface is automatically switching from direct monitoring to input monitoring when recording starts, and various possible sources of attenuation (including possibly +4dBu vs. 10dBV line levels and balanced vs. unbalanced cables) are coming into play when input monitoring that are not present when direct monitoring.
 
SONAR doesn't support ASIO Direct monitoring, so I'm not sure how that automatic switch would be happening, but nothing else really makes sense.
 
One thing to check would be to plug your headphone into one of the synths and make sure it's not the synth that's changing volume in response to MIDI CC7 coming from SONAR's track volume setting or something like that.
 
EDIT: On re-reading, I'm starting to wonder if your getting some phase cancellation issue from having SONAR's output going to the mixer from the interface, and then being fed back to the interface by the output of the mixer. In general it can be problematic to use a mixer to manage both input and output signals to/from your interface as it sounds like you are doing. I've done it to take advantage of the mic preamps on my Mackie, but you have to be very careful how you have things set up, and I would never route the monitor outs back to my interface directly.
 
 

Got pissed, closed. Came back later, listened, got pissed again ,tried again, VOILA! Perfect. Chalk this up to ghosts in the machine. So many pieces of hardware, changing miniscule voltages to ones and zeros, it's a miracle it doesn't happen all the time. Add that solution to the top of the troubleshooting list , especially if you KNOW you're doing it right. (I thought of the phase thing, so monitored from both the mixer and the interface, no joy.  Also thought of stray midi message being echoed by another track, so ruled all of them out too)marking solved with a shrug.