I am aware of the trend toward tiny, lightweight bass heads. That's all well and good, but what's the point if most speaker cabinets are just as large and heavy as they've always been. I am genuinely perplexed. Other than perhaps using a tiny bass head for practice (with headphones) or maybe the studio, what's the point of having it in a live setting?
I've gone thru buying & trading a 1/2 dozen amps & cabinets in 1 years time, to fit my needs for a new band I joined. And tried everything on the floor at 4 GC locations within reasonable driving distance. There are some great lighter weight cabinets, but only good for a 4 string. These light weights cannot handle the low B of a five string. Not even the Fender 500 or the Mark Bass 2-10 @ $1,200 bucks!
What did I end up with? Three amps to fit different power needs. All three handle the low B & even B-flat tuning.
Small gigs or small stage, Acoustic MKII. 100 watts, 1 - 10", & front port. Not talking much weight here as its small. But it's a cool mini-stack version. I use an amp stand to tilt it some. You'll see why further down.
Larger gigs, no PA to DI to: Carvin B 1000 head with Carvin BXR 2-10, front port. Small, portable, cab weighs 58 lbs. 4 ohm cab at 600 watts rms, head can run 600 at 4 ohms, 900 at 2 ohms, 300 at 8 ohms. More power than you will ever need. Handles low B like you're playing a 4 - string.
With a PA & sub, Ampeg BA 2-10 V2. 280 watts, can be 450 with 2nd cab, but I don't need it. It's a tilt-back design, and I use it as a "bass" stage monitor.
Too many bassist's go for the huge, powerful, tall stack. Why? Cause the low frequency of bass waves are 20 feet long. You can't hear them even if they're blowing people against the back wall. Hence your always told you're too loud and you can't hear poopie above the rest of the band unless you crank it up.
The tilt-back Ampeg as a stage monitor for bass only solves the problem. Tilt it back, placed in front of you, problem solved. No more monster bass riggs needed. But do back off the bass knob a little or it will bounce off the back wall and vibrate your bandmates skulls.