The Fender Studio Bass is for me, one of the greatest all-tube bass combo ever. (But I have never tried out the Trace Elliot or the Mesa Buster combos that have been shown here!...would like to.) Made from about '78-'81 I think, these were 180 to 200 Watts, from 6, 6L6GC tubes. I have two of them, I like them so much.
How many players have given up on their Bassman heads because, despite their great tone, they just cannot produce enough volume? Essentially, this is a Fender Bassman that has enough power to actually use in a rock band. And with both an input gain volume, and a master output volume, (and also a five-band EQ), lots of warm tones can be dialed in, even at low volumes.
The downside is that these are top-heavy and quite awkward to move, at around 95 pounds or so. They are a good candidate for having their head removed and re-cased in a reproduction case (as in the last picture here). The combos show up on Ebay occasionally and they usually go cheap (like <or=to $800). In Europe, scarcity drives the price a bit higher, over $1K in this case
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320506675941&ssPageName=STRK:MEWAX:IT
One other negative is that these amps have only an 8 Ohm tap on their output transformer. So, an extension cab cannot be added to the combo, despite there being enough power to drive more than just a single 15. The separate head version I have will drive a Bag-End 4x10 nicely, but always the total load must be 8 Ohms.
As a plus, there is a very nice (unbalanced, but clean) line output on the back which can drive an external power amp and cabinet perfectly. It is a post-output transformer line-out, so it carries all of the power tube tone and not just what the preamp provides. Many DIs that can handle a line input (like a Countryman for instance) work fantastic if connected to this line out........all of the power-tube tone in a DI line, with no need to mic the cab. I don't have a recording to share, but this DI arrangement sounds great.