They may or may not actually refund. I know when I got the RE0 way back when they first came out, I returned them within the trial period and got store credit. I ended up spending a bit more and grabbing the OK1 buds. I don't recall if that was my only option or if there was a fee if I didn't. If you get a full refund, fine. If you don't, I might suggest paying a little extra and grabbing the RE252. The RE252 has a number of counterpoints to the RE0 to if the RE0 wasn't your thing the RE252 might. I'm just tossing out the suggestion depending on how their return policy is set up. It's been a couple years, so I really don't remember. The DBA-02 is of course a smart buy too and excellently priced.
I may also suggest you look into a more robust amp option. The E7 is a nice upgrade from the E3 and E5, but it really isn't a power increase. For something like the RE0 and some of the other nice earphones out there, more wattage is desirable. A good suggestion is Practical Devices XM5 which has excellent internals and has a slew of extra features like bass and treble boost, variable crossfade, and 75ohm patch through for some of the more sensitive and easy to drive earphones. I know we talk headphones here a lot, but a solid amp is just as important for getting high quality sound. An amp with a built in DAC just takes it further by offering a solid source device for less than stellar players, i.e. cheap laptop audio. It's just something to think about along with searching for the perfect earphone. It's a product you'll buy once, and it will provide a rock solid bass for everything you attach to it.