Small, cool, efficient amp needed!

[empacher]

pro-ject audio box S series. don't know much about there performance but they are tiny digital amps.

http://box-designs.com/main.php?info=amplifier&cat=amplifier&lang=en

 

[bigboss]

http://shop.xtz.se/dsp/a-800

 

[tino]

Some very compact Class D amps with digital inputs:

* Teac A-H01 (about £200)

* Nuforce DDA100 (about £500)

Also, you might find a Wadia 151 ex-dem or used that's within your budget.