That makes sense.
I'd still encourage you to see if there are desktop DAC/headphone amp options in your area. I have owned the E17, and it's great for a portable amp, but a good desktop dac/amp would be worth it for having a great sounding setup with such good sounding headphones.
Also, if there are places that you can order from that don't take as long to receive the item, you might consider that. I just got the Meier Corda Rock desktop amp from Germany (free shipping internationally), and it was pretty quick for me. (a little over a week). Then the Objective 2 and ODAC, which many on Head-Fi consider as a reference quality, is an open source design that's built by many companies around the world. It's superior to the FiiO products, and always possible maybe someone is building and selling them local to you or selling them somewhere that would give you better shipping.
One way around import taxes some people find (depends on your country) is to order a separate DAC and headphone amp, but from different locations to keep the cost of the items down when going through customs.
I've also owned the STX. I think it's a bit better than the E17 in overall sound quality. However, soundcards can be subject to EMI from your computer. So you might get it and have noise problems. That's why if you don't need the digital sound processing of an internal soundcard, most Head-Fiers will say go with an external DAC/amp setup.