I can't compare this with other tube amps (I come from a solid state background, but I can tell you this - the sound is detailed, clean and naturalistic. I can follow basslines better with this amp than any other I have heard. The imaging/soundstaging is great - its not like other amplifiers - its a little hard to describe, but it can be very impressive.I guess there is alot to be said for good circuit design and sensible parts selection, as opposed to needless complexity and expense.
My only "reservation" is that I would love to hear the MAG15 - more power and punch.
Of course all this is completely subjective
I have a pair the Bob Brines FT1600s (mark 1).