Umm...
At max volume? What is max volume on TR-Amp? The knob turned all the way up until it cannot turn? I'm pretty sure you would damage the headphones if you turned the knob of the TR-Amp to the max. That sounds insane.
There is not way you are turning them up past 12 o'clock. I am getting noticeable noise at 12 o'clock - if no music is playing, you will hear white noise in the headphone. If you cannot hear it, your hearing is either damaged, or it's my TR-Amp unit that's faulty. However, I don't think it's my unit. I had noise with Kbear TRI i3 too, but it's a planar-magnetic IEM, so it's normal.
George, give me more detailed answers. I need to figure out what's the problem.
Edit: I want to say that I am a loud listener to, and listening to the SR2 at max volume of TR-Amp doesn't sound real. I only push the TR-Amp to the max volumes with planar-magnetic headphones (like I did for the Hifiman Deva), but none of my dynamic driver headphones passed the 3 o'clock mark (on TR-Amp knob). So please clarify.
If anybody else has the TR-Amp and the iBasso SR2, help me out. The noise starts at around 11 o'clock I believe, and should be noticed by any ear at 12 o'clock. Do not play any music, just without music there will be noise. And, I am not talking about the noise you get when you turn the knob on the TR-Amp, just clarifying.