The better amp?

sorry, what means discrete in amps? thanks

Ok, I already read it, but according to what I read in the description of Texas Instruments for the TPA6120A2 is this: 

In applications requiring a high-power output, very high fidelity headphone amplifier, the TPA6120A2 replaces a costly discrete design and allows music, not the amplifier, to be heard. The TPA6120A2’s current-feedback AB amplifier architecture delivers high bandwidth, extremely low noise, and up to 128dB of dynamic range.

Three key features make current-feedback amplifiers outstanding for audio. The first feature is the high slew rate that prevents odd order distortion anomalies. The second feature is current-on-demand at the output that enables the amplifier to respond quickly and linearly when necessary without risk of output distortion. When large amounts of output power are suddenly needed, the amplifier can respond extremely quickly without raising the noise floor of the system and degrading the signal-to-noise ratio. The third feature is the gain-independent frequency response that allows the full bandwidth of the amplifier to be used over a wide range of gain settings.

@auxinput, thanks, but I just want to know between those 2 amps and the Roland uses USB power, is a audio interface via USB.

@auxinput: Which of the specifications of both amps do you see best for audio quality? I wrote the link for each one of the Texas Instruments page.thanks.

I made a comparison between the Emotiva XDA-1 and the Roland Mobile UA and I am very serious about it, the Mobile UA is much better than the Emotiva, a lot more detail, more clear ... that interface can be connected to studio monitors In a balanced way, it is exactly the same as connecting it to my two Crown D-75 amps, the active studio monitors(active), as you should know, have their own amp, I have the amps alone with speakers connected.

@auxin @timlub, thank you guys for the info. I'm just learning here...