I’m currently running an Ampeg SVT IIP tube preamp through a PJB big head with headphones it’s sounds sweet.
I do sometimes run it through the effects loop of a battered Ampeg VR and SVT 210 HE
With the option to plug my iPhone into the big head also and play as loud as I can handle with media included im finding I spend more practice time on the PJB.
I’ll drop this in here from the PJB website as it’s something I haven’t tried
A more important function of the BigHead is being a recording tool both in digital and analog. As an Analog Digital Converter, it has the finest BURR BROWN digital components. The USB out is 48KHz 16Bit digital conversion. In other words, recording your bass into Pro Tools will give you exactly what you wish for and absolutely nothing else.