THX certification is totally meaningless on a laptop.
This kind of certification has a number of levels depending on the final output frequency range, volume and quality given to loudspeaker systems, primarily those designed for "cinema" quality sound.
https://en.wikipedia.org/wiki/THX
... and more recently applied to LED displays, although some of the best and most expensive monitors in the world never use a 'THX' certificate to sell their product, since it's a gimmick.
It's largely meaningless for most consumer situations and used primarily as a marketing point like "HD Audio".
The reason you find that the FiiO is 'less punchy' than the Razer, is most likely due to post-processing audio software bundled with the laptop that boosts treble and bass frequencies.
Often this software bloats the bass to insane levels far from anything resembling a high-fidelity experience.
But if you're accustomed to this kind of sound, something truer to real life (like the FiiO) may sound boring, stale and unexciting, despite actually being objectively better.
