I bought one of these new off eBay specifically because I want a small combo that can fit inside a regular suitcase (carry-on or checked) that allows me to play without a drummer, along with a pair of acoustic guitars. It has 2 4" speakers and a 70 watt amp. Comes with phones out/aux in and the aux has its' own level control. I paid 400 using best offer.
The fit and finish are beautiful. This looks more like a high-end audio toy than a really small bass amp. All the controls feel smooth and solid. The sound is what I expected from PJB (having owned the 4B combo and ext cab a few years back): clear and uncolored to my ear. Volume when cranked is easily enough for my goal of being heard along with 2 unamplified acoustic guitars, but I'd never consider it for anything louder.
In comparing it to my GB Shuttle 3.0-8T combo (single 8" speaker and the Shuttle 3 head that pumps 300 watts into 4 Ohms), the PJB is nowhere near as loud or as low......it's not even close. If I didn't have the extremely small size requirement I would have no use for the PJB. However, even though the Shuttle is almost as small, it's shape makes it far less suitcase-friendly. The Double 4 is only 6" high, so it will fit better. The other area where the PJB excels is fit/finish. If you want a small amp to leave on a desk and you are willing to pony up cash for something that won't look out of place in an executive's office or a living room, then the PJB delivers. It can also double as a great computer ext speaker.....the better to hear the clips posted on TB
However, if you care about absolute volume, I would strongly advise another option. Too bad GB doesn't make the 3-8 combo any more. It's waaay louder and deeper (and every bit as tonally satisfying) and the head can pop out and provide real gig-worthy power through a larger cab.
I'm pretty sure the Markbass 8" Micromark will also crush the PJB for absolute volume, although it's covered in (IMHO) gross rat fur and has no standard tweet, so it likely won't sound as good for aux music sources.
Larger PJB offerings are laggards in terms of volume /lb and volume/$ compared to the competition (this isn't an opinion, it's a simple fact inherent to the larger ratio of metal to paper when choosing numerous, smaller drivers over fewer, larger ones, as well as inherent disadvantages in total displacement and sensitivity) but have a superb fit and finish and nice clean sound. For me, there's no real competition in something this small, however, and I'm keeping the double 4 for travel. I reiterate, however, that the Suttle 3-8 combo is only 3 inches "thicker", and sounds
easily/subjectively 3X louder and deeper.