Zoom B1 FOUR Bass Multi-Effects Processor with 70+ Built-in Effects, Amp Modeling, Looper, Rhythm Section, Tuner, Battery Powered

If you are primarily going to use headphones, the 25 is fine. Honestly, most of my headphone practice is through one of THESE (I have the version with the pedal, I think I paid around $75 used from guitar center website). Also looking at prices, I hadn't realized how expensive a new Rumble 40 is now. I think I paid around $100 used locally. While the 40 is definitely the better amp, the Rumble 25 for $100 less is a solid deal and a good way to start practicing.