| I have both and use them interchangeably on the gig. In my opinion, they are more similar in tone than different at the low volume gigs I generally play - musical theater. Some here have characterized the Neo-Pak as being slightly more full in the low end than the Shuttle 6.0. To my ears, if that is the case, I find the differences to be very subtle. Note, that I use the older Bergantino HT112 and EX112 speakers, generally only one, but for the occasional higher volume gig, both. I also did an extensive A/B comparison between the Neo-Pak and the Shuttle 6.0 using one of the newer HT112ER speakers at Bass Specialtes in Bensalem, PA. Again, to my ears, only very subtle differences in tone between the the two heads. Love them both, however, the SL600/900 is sure piquing my interest!
Cheer,
Dennis | 
