Looking for an amp for Senn HD580 and Grado sr225i

I am currently in the market for 2 amps:

1 for home use:

I already have an Emu 0404 usb (might switch to Asus Essence ST or Halo Claro since I do not use any of the recording utilities).  My headphones are Sennheiser HD 580 and Grado SR225i (future).

I am willing to spend up to $200.  So far I have seen the HifiMan EF2 and Little Dot Micro III recommended, but I am wondering if there are others out there.  Also the IBasso D2+/D4 and audio-gd sparrow.

1 for work:

I cannot install a soundcard, so the output will likely be usb: 

I have been considering a usb dac/amp combo.  So far I have been looking at the NuForce Icon uDAC2 and the Fiio E9/E7 combo.  Are there others I should consider or are these the best for the money?  If they are the best for the money (under $200), which would you recommend?  I will be using Ultimate Ears TripleFi 10 and Ultrasone HFI 780 (future).

Thank you for the feedback.

For portable use I have a clip+ and do not feel the need for an amp. (have the Ultimate EArs, Koss KSC75, MEelectronics M6).

any advice?

What would my budget need to be to see an improvement?

Would it be worth saving up for a Crack: Bottlehead OTL, Nuforce Icon/2, Meier Corda Swing, Schiit Asgard, Darkvoice, or Matrix M-stage?