I have been in a similar predicament because my research sometimes takes me abroad for a semester or more. These days, streaming is the way to go, and the easiest way to do that now is to use a Chromecast Audio (if you have decent wifi). Its analogue output is more than good enough for a modest system, but it also has an optical digital output.
On the amplification side, any amplifier in the 2x50 watt range from mainstream manufacturers like Pioneer, Yamaha, Denon etc will be fine. Try to spend as little as possible on electronics, although digital inputs may be attractive in the long run. One thing that I have found attractive in a bedroom system is an auto on/off function. Not many amplifiers have it, but with it you don’t have to get out of bed to turn it on or off, and you can leave it somewhere out of sight. A class D amp usually runs cooler, and is lighter to transport. Here, active speakers often have an advantage as well.
Leave as much as possible for the speakers, as these are the part that actually defines the sound quality. Years ago I bought a pair a Rogers LS3/5a speakers for this purpose, but they were too heavy when I had to take them on a plane, so I later bought a pair of much lighter Wharfedale Diamond 9.0’s. My last fellowship was in Princeton, and these days you can only take one rather than two suitcases on such intercontinental flights (I am Dutch), so I had to downgrade again: I took my little Tivoli Audio Radio Two, plus a Behringer UCA 202 usb DAC connected to my laptop, and playing TuneIn internet radio and Spotify. Of course that was not audiophile quality, but much better than nothing, and quite enjoyable.
