Hey Taveren, unfortunately I don't. You know, I'm sure the 15 and 11 sound very similar, but if the T50RP is going to be your primary phone I would go with a 'brighter' amp, because the T50s are already very warm and lush in the mids. I think there's a chance they would sound too dark. As I mentioned above, I will probably apply equalizer to my ZMF to get a drier sound in the mids. If I had to choose between the 15 and 11 again now that I am familiar with the sound signature of the T50RP, I would definitely go for the brighter amp, the 11.32, since reviewers seem to agree that it is a little less 'warm'.
To my ears at least, almost all headphones reproduce forward mids (or the perception of forward mids), everything I've heard including and especially the Sennheiser HD6xx. This 'problem' is only successfully resolved in higher end, more expensive headphones, such as the Beyer T1 and HD800. If you compare the 800 to the 650 the first thing you will notice is that the 'lush' mids, the signature of the 650, are gone, this lushness is just a forward presentation imo. So for my tastes and perception of sound, it was a no brainer to get the 'brighter' amp as I'm not a huge fan of the mid centric sound of so many sub $1000 headphones. To me it is distortion.