Hi Jon
It's funny you mention Dartzeel vs Dagostino. I've been thinking about this dilemma and while I think the Dartzeel is a better amp overall, I may have to admit my Dagostino sounds a little better on my TADs - for my preference. I am not sure I'll make sense but here goes. The Dartzeel has more details without being harsh. The Dartzeel has an amazing ability to get out of the way and let everything through without changing it. Because of what I hear on my TADs, for my preference, the Dagostino ever so slightly rolls off the treble making the more unforgiving recordings more listenable. BUT, when the source it perfect or nearly there, OMG! The Dartzeel just does it for me. The D'Agostino has little more thicknes or fullness that works great on some music but not so well on other music. I'm learning you can't have it all. Yet!