I toured in a nightclub band for 3-years back in the early 70's playing 5-nights a week, 50-weeks a year. I started out with the 1966 Fender Bassman amp that I bought new in 1966 and played through high school and some college. It was a 50-watt all tube amp. It sounded great and since it was the first year they put the big cab on the Fender Bassman, it looked great too.
About 3 months into touring in 1971 the keys and the guitarist bought Vox Super Beatle amps as Thomas Organ was clearing them out. IIRC those were 125-watt amps (solid state not tube). They promptly buried and kept telling me that I need to turn up. If I turned that Bassman up past #7 it would fart out. Very few things as bad as being told to turn up your bass when you don't have the ability to do so.
While we were playing a club for a couple of weeks in Lincoln Nebraska I went to the music store looking for a Fender Dual Showman (85-watt all tube) and came out with a Standel piggy-back MCIIB/SAM30B amp (200-watts rms). That totally buried the Super Beatle amps. I couldn't turn it above #3 indoors (9 o'clock). Finished out the next two years touring with that amp. I could turn it up to #5 outdoors but it definitely had more than I needed. I learned the very important lesson that having too much power is far better than not having enough.
So, don't buy something that you know you're going to have to replace down the road. If you like the warmth that tubes provide, look at a Hybrid amp - one or more tubes in the preamp and solid-state power section. There are also chips such as the "Golden Ear" chip (THAT-4001) that will provide that same warmth. I have an Eden WT500/800 that is a hybrid with a 12ax7 tube in the preamp. It has a very nice warm sound while still being very clear and articulate.
I also have a small Eden class D amp, a TN226, that is a 225-watt amp that weighs all of 4.7-lbs. It does not have a tube and yet, it still has that same warm sound that my hybrid does because of that "Golden Ear" chip. But 225-watts now days is not much power and I specifically got it to play a small venue that we played a lot. Class D amps are super light (mine weighs 4.7-lbs.) and I could put it in a shoulder bag, grab my 112 in one hand, bass in the other, and load in was done! My plan, once we start gigging again is to get a [Invalid or Expired Link Removed] which is a class D amp (4.8-lbs.) that has 800-watts rms power along with all the goodies. It also has that nice warmth to its sound.
You can hear that DNA-800 at the video below as Bass Musician Magazine.com goes through all the features. You'll notice the nice warm sound it produces through that DNS-210 cab:
So, don't think that warmth can only come from tubes. A hybrid amp or just one with the right chip in it will give you that warmth. If you really want an all-tube amp, then get an 80-lb., 300-watt monster and call it good, but please don't settle for a 100-watt all-tube head lest you find yourself in the position I was in back in the early 70's...you really don't want to go there.
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