As for this particular amp, it's tough to find info on it. But from what I can gather, it's 35 watts, powered by 2 6eu7s and 2 6L6s. The design is actually really similar to the B15N, except this also has separate inputs for guitar and accordion/mic. The bass input sounds like you'd expect - full, buttery B15 tone. The guitar input is a little brighter - but it's definitely more an Ampeg sound than a "Fender-bright" kind of sound, and it actually breaks up nicely as well.
One tube has a loose piece in it but doesn't effect playability. Mullards in pre and JJs in power section. Really really cool amp! Add $30 for shipping