I own a 370 and have a friends 150b on permanent loan so to say. I gig the 370 and the second input has less output leading to me guess it has a +-5 to 10db cut intended for higher output basses. I used my ernieballs which are quite hot with the 370 without a problem. Plugged them into input 1 without hassle. I can't recall using active basses with the 150 though. Passive guy most of the time. For clean headroom the 370 is the way to go if you're into acoustics. GREAT amps.
Proudly using Musicman basses, vintage ibanez copies, and custom builds.
Amps: Ampeg b15n + Acoustic 370
Cabs: mesa 1000 + Ampeg Heritage 410
I stomp on EBS, EHX, and MXR pedals.