It’s significantly brighter to my ears, much more treble presence. I would nuance the A-01 is warm summary... to me A-01 is rather warm natural. it’s not that warm the lower mids are not overly present, warmth is trickling down from the mid and upper bass. And it’s not dark either, lower treble has this yummy weight to the notes, upper treble is very refined on the A-01 and with a warmer tone... just less forward and clear up top than T-01.
One key difference between A-01 and T-01 for me is the A-01 is thicker, has more body and weight, more macro dynamics, the textures are richer. I hear lower treble having quite a bit more energy. Soundstage is taller and deeper to me. T-01 is thinner, with better separation, wider soundstage, there is more sub bass and upper treble presence is greater. Mids are neutral to me, more reference. If I had to categorize I’d say neutral with a touch of brightness but it’s elegantly done. There is to me no real warmth from mid/upper bass or lower mids, but good sub bass slam and lower bass presence.
I’ll test the Phantom with the T-01, with the A-01 I do like the pairing it’s not as warm as one might expect... I figured it would make the Phantom even thicker but it does not emphasize thickness further. Bass has great snap and control and upper treble are not rolled off just feature a warmer tone and good weight to the lower treble.