As an Ashdown fan, and I've had loads - abm2, mag, superfly, lg1000, rm500 and x2 abm600, I'd recommend a Gallien Krueger Fusion 550.
Dont get this mixed up with the fusion series or the mb range. The 550 (not 500) is the valve / solid state hybrid.
Weighs similar to the abm600 but for me it's much louder, much punchier and much warmer.
It also has 2 channels, a big valve preamp and a superb sound, as well as memory for saving your settings.
It sound very valve like and has an instantaneous response.
Sits in the mix really well and is just right for me.