Line 6 has introduced two interesting amps. They are aimed at guitarists but have some interesting features for amplified strings as well.
The two amps contains a full-range speaker system and 75watt and 150watt respectively and can be configured via an iOS app, for either ipad or iphone.
This way the tone can be highly customized for hard to amplify instruments such as stringed instruments.
Learn more here: http://line6.com/amplifi/