Daisuk is asking for apps that generate sounds the OT can sample. Android’s audio latency doesn’t really matter for that. FWIW, depending on the device, it could have a really good DAC on the headphone out or a terrible one. The Galaxy Note 2 I used to have had a Wolfson (nice) DAC, the Note 1 before that was some crummy Yamaha.

Daisuk, you can also look into:
RD4 (acid groove box)
Reactable Mobile
Sunvox
SPC (MPCish)
G-Stomper (getting a synth iirc)

There are more on the Play Store, but those are the ones I’ve used or demo’d. Been awhile since I’ve used them, though.