Sorry didn't typed the name completely, should be Focusrite Saffire LE:
http://www.soundonsound.com/sos/jul06/articles/saffire.htm
http://global.focusrite.com/downloads?product=Saffire+LE
http://d3se566zfvnmhf.cloudfront.net/sites/default/files/downloads/7059/saffire-le-user-guide-1.0-english1.pdf
Only mentioned in the manual:
HEADPHONE MONITORING
• 1 x 1/4” TRS Jack on front panel (mirrors outputs 3-4)
• High power headphone driver
I used it a few years ago when I wrote review of Beyerdynamic T1 for Headfonia:
http://www.headfonia.com/first-impression-beyerdynamics-t1/
The Forte headphone output at 27 mW @ 32 ohm doesn't seem to be powerful, but should be sufficient for MSR7. It's about the same as 30mW x 2 output power of the iPhone classic, which is ok, but cannot be considered powerful.
If you want to connect Forte balanced TRS output to any headphone amplifier unbalanced RCA input, use cable connection number 10 from the table in RANE recommendation of audio interconnections:
http://www.rane.com/note110.html
I had W1000X a few years ago, and currently writing review for W1000Z which I consider a great improvement of W1000X.
From memory of W1000X, I strongly suggest to use MSR7 for any professional audio tasks, composing, recording, mixing, etc, rather than W1000X. Although W1000X is really a nice headphone, it has it's own flavor, and the flavor is rather strong, especially in the emphasize on the upper mid - treble area, making it not flat enough for Pro Audio related tasks. MSR7 is closer to flatter tonality when compared to W1000X. MSR7, still has some mild forward midrange and emphasize in clarity, but MSR7 sonic flavor is milder than W1000X. MSR7 in my opinion is more suitable for your piano composition.
If you don't mind to share with me one of your 'copyright free' composition, I will use it for my future AT-HA22TUBE review. I will try to record the output of the tube amp comparing with the output of solid state amplifier, to hear if we can hear any difference