These don't touch the Alpha Primes. Alpha Primes has bigger soundstage, better extension in the treble, tighter, faster bass with less decay (by far). The mids on the primes are glorious, whereas on the THX00 they are somewhat recessed. The Primes have a much more neutral signature, and the treble is adjustable so they can get reasonably airy. The THX00 have more of an airy experience, though I don't think they extend as far as the primes. The subbass is killer on the thx00 for an emphasized subbass, the primes bass is exceptional, but neutral.
They are both excellent headphones for their prices, but they are very different. Don't fool yourself into thinking the thx00 reaches to the level of the primes, just enjoy them for a great deal at $400. Primes are on another level imo, but you have to pay for it.