The Bassman 300 is a Fender re-badge of the new/"old" (discontinued in 2004 or 2005) Sunn 300T. I had one for two years and sold it. It's the ONLY bass amp of mine I have ever sold. I consider them unreliable, poorly designed, and just outright BAD sounding.
I only bought mine because I got in a huge debacle in the very first days of Talkbass with Rich Briere over a demo of the amp when it was new. I tried five or six of them in stores, all new, and not one functioned properly and one actually caught on fire. He promised to ship a certified functional model to my local Fender dealer, publicly on the forum. A few weeks passed and the amp never turned up with the Fender rep at my dealer's, so I questioned Rich about it. Even though his prior posts were plain for anyone to see, he denied ever having made them and threatened to sue me through Fender for slander for justly calling him a liar. He eventually threw around enough ad money that Talkbass's admins went back and edited our exchange a week after that to make me out as being in the wrong, and Paul Determan, TB's owner at the time, even went so far as to post my full real name and mailing address so I could be served by Rich without my consent.
So when I found a used 300T at local store that ran with no issues, I bought it and used it pretty often at band practice. It never broke down, but it never sounded good to me or the rest of the band. The guy I sold it to ended up loving it though, so to each his own I guess. I like what Fender has done on the tube guitar amp side of things, so maybe they can get one right, but I'm not holding my breath.