Firstly apologies if i should have posted this in another thread - i think i read all the relevant stickies and found nothing...

so i'm looking to buy a loudish (pretty much so i can hear myself over a drummer + small gigs) bass amp, mainly gonna be playing old school 60s/70s stuff - beatles, rolling stones, etc. However i'm not really sure where to start looking - i've seen amps like the marshall MB range and fender bassman and they are the sort of thing i'm looking for in terms of power/price (i think 150 watts would be sufficient for what i have in mind?) but i'm not really sure what other sort of things i should be looking for. Also - the fender bassman seems to be a transistor amp, while the vintage one which i love the sound of is valves (i think), but as far as i'm aware fender don't make them with valves any more. Will the transistors make any difference?

Cheers, any general advice would be appreciated. if it makes any difference i'm playing a hofner contemporary series violin bass... (yeah pretty much a beatles nut)