Portable amp for Beyerdynamic T1?

Oh, yeah -- budget is $250ish.

And tubes are out, too fragile for this purpose.

Oh, and the source will either be my laptop or iPhone.  So built-in DAC will be valuable.

I have the T1 version 3. 

It will be more business travel than personal, from here on the west coast to corp HQ in Boston, so a longer flight and often a stop (most of the nonstops are redeye, which I'm not doing).  There will be significant time both in the office there and in the airport/plane/hotel -- maybe I'll give your Bose suggestion a spin and see how it goes.  I've actually got a Bose wireless headset that they sent me for my home office, it may well be Quiet Comfort. 

My amp at home is not a small footprint -- ModWright LS-100, quite large for a preamp, actually. 

Thanks to everyone for their comments.

Turns out I've got both my own personal pair of sony NC phones (MDR-ZX750BN) and my company-supplied Bose QC phones.  I'll take both on my next trip and see which works better on the plane.  I've used the Sony on the plane in the past, and they were good at canceling noise and gave decent sound quality, but I was aiming to improve my sound quality if I could.

@yage -- I can stretch to $300, will read some reviews on the G5 to see if it works for my use cases. 

I ended up buying a Topping G5, thanks, @yage.  Looked like just what I wanted.