Well I'm not sure how helpful this is because I'm really new into headphone rigs. I'm primarily focused on my 2 channel home stereo. I bought my first set of cans about 6 months ago, Senn HD-600 and my first amp, RSA SR-71A. I recently purchased the Pico amp/dac to compare the two amps. My experience is limited to those two amps. As a source I'm using my Macbook Pro, WAV files, using Bitperfect software. I've never heard Ibasso amps.
I have to say that I'm very impressed with the Pico amp/dac. Using the usb dac sounds 100 times better compared to listening through the mini input. Using the dac, it sounds very open, neutral and revealing. It's also smooth, with no digital etchiness.
In some ways it is an unfair comparison to the SR-71A because the SR-71A doesn't have a dac, so it's using the cheapo dac inside my laptop. To put them both in the same playing field and evaluate them both using the mini input, then the RSA is the easy choice. RSA is a tad warmer and has great slam and authority. It's very musical and hard not to like.
Now using the Pico dac vs the RSA- that is a very difficult decision. I'm still contemplating which amp I like better and I haven't decided yet.
If you get the Pico or Predator, please post your impressions.