Yep, it uses the Texas Instruments 6120A2 (80mW @ 600 ohm) headphone amp, which is the same as in the STX
They also both use closely related DAC chips, the Burr-Brown PCM 1792A in the STX and the Burr-Brown PCM1794 in the ZxR.
Sound wise they should be pretty much indistinguishable but the ZxR does come with a much nicer package. Also, the virtual surround processing is likely to be better for games using the ZxR as the Creative solution is simply better than Dolby Headphone, which is more aimed at home theatre than gaming.
One area I would be careful with the ZxR is headphone choice. You'll be fine with your 600ohm Beyers but should you think about buying new ones in the future, you will need to consider the damping factor effect. The problem is that the ZxR has a stupidly high output impedance of 38ohms, while the STX is 10ohms and my Schiit Audio Magni 2 is only 0.1ohms. This starts to really matter when using low impedance headphones and the majority of new headphones are 50ohms or less. The only way of knowing if headphones are sensitive to low damping factor is to listen to them with your equipment but a good indicator can be seen by looking at frequency/impedance graphs, which are available in a few places. Ideally, headphones should have an input impedance of at least 8x the output impedance of the amp. So susceptible (and not all are) headphones would need to have an input impedance of 8x38, or 304ohms. So something like the Sennheiser HD650 would be fine as they are 300ohms, whereas the Sennheiser HD599 would be bad as they are susceptible (their impedance varies dramatically with frequency) and only have an input impedance of 50ohms.
anyway, that's something to consider way on down the line, now is time to just enjoy your shiny new card and Beyers.
I'm hoping it's a little better, one or two reviews pitched it as the best sound card they'd used so I guess we'll see.