You should give the Vioelectric amps a chance, they can be integrated a DAC too if you pay extra I think. Give them a listen for long periods though, they don't sound all that great with some headphone. Vioelectrics are pretty neutral and analytic, so should do brilliantly with the TH900. I didn't bring the vioelectric amp with me when I went to the headphone shop I went to so can't say too much about what they acutally sound like. also, I actually forget the model names so you should take a look around. Hope this helps
I found Violectric HPA V100 amp owner forum friend in my country . As far as possible I will try them!
Thanks for help!