It's hard to go wrong with iBasso's product, especially when you can test it out at Jaben to see whether you like it. The additional amp section can be considered as a convenience, for example when you cannot bring your (possibly) desktop amplifier with you, unless you're 100% certain that you won't be needing the amp section. Even so, you can just use line-out to utilise the device's DAC section.

Only the headphone out, as the line-out bypasses internal amplification for iBasso products. Consider the iBasso D12, the successor to the D10, or if you don't need the additional connectivity functions (optical and coaxial), the iBasso D6.

I've tested the D10 and I wasn't impressed by it at all, compared to the iBasso D6. Unfortunately, I couldn't give you a direct comparison of the D10 and the D12. Why not let your ears decide? I'm quite sure you'll go for the D12 too