I mentioned this a while ago, but here's my latest update. I've been using a PJBD4 with a laptop battery over 8 years with my bass ukes for most rehearsals and gigs my uke group does. A couple of years ago I bought a used one here on TB as a backup. A short while after, I wondered if I could hook them together, so I contacted Phil, who told me to Line Out from one, to Aux In with max volume on the other, which would allow the first one to control the volume and EQ on both, plus make it a 4x4 140w rig.
I tested it, which worked very well, but to stack them, I had to extend the feet on the bottom of the main one. I used the setup a couple of times, but it was a bit inconvenient transporting them in their own Arriba gig bags, and sitting one on the other precariously. So I decided to attach them together with metal brackets on the four corners, plus I added snaps to a carry handle I had in a drawer, that I attached to the top carry handles. I'm looking for a proper size gig bag, but for now will just not use one.
I tested it, which worked very well, but to stack them, I had to extend the feet on the bottom of the main one. I used the setup a couple of times, but it was a bit inconvenient transporting them in their own Arriba gig bags, and sitting one on the other precariously. So I decided to attach them together with metal brackets on the four corners, plus I added snaps to a carry handle I had in a drawer, that I attached to the top carry handles. I'm looking for a proper size gig bag, but for now will just not use one.