Boss Micro BR80 as interface

Hello everyone.
I have a question that you might know the answer.
I use Sonar Professional for recordings and now I am using the Boss MicroBR 80 as interface for recording guitars, bass and vocals.
Everything works fine except for one thing. When I set the levels for recording on one track, I get peaks around -7 or -8 which is good for me. I record tracks without clipping and the sound wave looks fat enough.
The thing is, when I hit play on that track, Sonar plays it at a very low level, about -60.
Even if I Boost the track and put the volume fader up (to max) it still doesn’t get above -55. If I use compression, the plugin squashes the sound very much as it should if the level was to high...but it isn’t.
I’ve recorded before with Boss BR800 and didn’t have this problem. I am pretty sure that I’ve already recorded with the MicroBR 80 and didn’t had this problem.
Maybe I set something wrong in the Sonar “Preferences” by mistake.
Anyone can help me?
Thank you very much.

Useful PDF here with all the set up info for using it as an interface;
 
http://cms.rolandus.com/a...media/pdf/BR80WS05.pdf

Thank you for your help.
I guess maybe the problem is that I was setting the sonar track input to receive the BR80 channel 1/2 stereo signal, and the instrument is Mono. Although it only records a single wave (Mono signal) maybe the signal is lacking the other side.
I’ll try to change the Sonar’s track input to only “track1 left” instead of selecting “track1/2 stereo”.
Thanks again.
PS: shame on Gibson for discontinuing the Sonar family. I’ve subscribed the rolling updates for 1 year in October and only got 1 update. We should be reimbursed for this.
As soon as I can, I will change to Cubase or Presonus using the “crossgrade” option, which is half the price.