I would say sell it. What you'll be looking for is a mixer with channel inserts. I have
the Mackie 1402-VLZ Pro with channel inserts on the first six channels. These act just like your main outs do but they work for each channel. For example:
I plug my keyboard L-out into channel 1 of the Mackie. The keyboard R-out to channel 2. My microphone into channel-3. My guitar to channel 4.
Now using the channel inserts, I plug into the channel 1 insert and direct it to channel 1 of
my Layla24. I do the same for the other channels Key-R ch-2 insert to Layla-in 2. Mic ch insert to Layla-in 3. Guit ch insert to Layla-in 4.
I now have four seperate tracks. Now once I have layed down the tracks into SONAR and applied the effects I want I have a couple options. One I can record them together to a final mix track 5. I can also send all these tracks back through my mixer using the outs on my Layla. Track 1 -> Layla-out 1 -> channel 7 on the mixer. Track 2 and the rest I plug into my other empty channels.
Since I no longer am recording, the only input the mixer is seeing right now are the outputs from the Layla and not the original instruments on the first 4 channels. This benefits me in a number of ways. I can apply EQ on each channel, as well a pan each track Left or Right. I can also adjust the faders as the song plays back to get the volume levels that I want.
In this case, I have connected the main-outs on the mixer to the Layla line-in 7/8 and am recording to a seperate track (my final mix track on track 5 in SONAR). It is common to make a number of final mix tracks along with individual instrument tracks to play around with. For example. Track 1 is just the keyboard. Track 2 is Keyboard with reverb. Track 3 is Keyboard with compression. Track 4 is Keyboard with reverb and compression. You can see now how the track count can really start to build up.
Saving everything to a seperate track, even if it sucks, is a good practice because it always gives you the option to go back.
Alright, so now we have recorded are final mix to a new track. Say you find something that you want to change, maybe just a backing off the reverb a little. Create a new track in SONAR, and do the same thing you did for your first final mix track. You can now compare the two and see if you like the improvements or if they suck.
In the above example, you don't have to keep plugging and unplugging all of your equipment which is something I find very useful.
As for your Behringer, make sure you've followed the level setting procedure for recording, like turning the volume up on your keyboard, turning up the trim, etc.
Good Luck