I've never seen one in person, let alone played bass through one, but I do have a few thoughts.
Sunn amps are usually pretty hi-fi, by which I mean that there is little coloration to the sound. I'd expect this from a keyboard amp anyway, and certainly from a Sunn keyboard amp. It's also what I look for in a bass amp. Additionally, I've played bass through several Sunn guitar amps, and have always found the result satisfactory, at the least. So I'd expect the same with this amp.
The tone controls won't be optimized for bass, so you might not get the exact response from them that you want, but that doesn't mean that the result won't be useful. Just don't expect the tone controls to make up for deficiencies in the speakers, if any.
I don't see a "normal" input, just hi and lo. I don't know if those represent hi and lo gain or hi and lo level inputs. Maybe someone else can tell you, but it wouldn't take long to figure it out. Just plug in and see which one gives you more signal.
What to expect? I'd expect a wide, flat frequency response, with little or no coloration. As I said above, I like that in a bass amp, but other people want more coloration for a "livelier" sound. In short, I think it would work great for me. Your mileage may vary, as we say.
What country are you in?
