I use a PJB Suitcase, with the two independent channels it's perfect for two instruments.
Although a bass amp, any acoustic instruments I've put through it sound absolutely gorgeous, guitar, bass, doublebass, mandolin, ukulele, 12 string.......
Masses of bottom end but sparkly clean top end with the 12 string or mandolin.
I absolutely love mine and am at serious risk of boring people rigid about it.