You could always subscribe to Bass Guitar magazine as they are offering a Blackstar Fly 3 as an incentive to new subscribers. The Fly 3 has an mp3/line input which you could feed from the headphone socket of your computer.
I use a Vox Pathfinder Bass 10, put my bass through a Tascam GB10 and feed the output from that into the amp.
I have used a Peavey 20w Minimax? with an 8" speaker which I liked and then regretted selling it.