My main amp is a MarkBass 121P, which is great for my band situation, but when I'm practicing, the fan noise and the hiss of the damn piezo speaker is distracting. About four months ago a Guitar Center discount code brought the price of a new PJB Double Four down to $400, so I ordered one to use as my practice amp.
There are other amps that would have been fine practice amps and would have been a lot less expensive, but I was drawn to its tiny size and the rave reviews. Indeed, the sound is amazing for its size, and I have no regrets.
However, there are a couple things about it I don't like that I haven't seen others mention. The first one is weird. When playing at louder volume, I heard distortion that was odd, and it wasn't from clipping. It took a bit to figure it out, but I found the extra sound wasn't coming from the speaker. It was coming from air rushing through the aux input jack! The case is sealed and the internal air pressure changes radically, forcing enough air through that port to make noise. I solved that by sticking in a jack leading to nothing, acting simply as a mechanical block.
The other issue is the tone controls. The unit uses DSP for tone shaping, and the manual says that as a result there is a lag between adjusting the knobs and hearing the result. But it seems like that isn't the whole picture. If I very slowly rotate a tone knob there are just 8 quantized settings for each of the knobs. As you rotate continuously, there is a stair step in its effect. It is a minor issue, but still disappointing that it isn't more continuous.