Dolphin SP-500BT
The SP-500BT is a Bluetooth speaker introduced in 2017 by Dolphin Audio. It was made in China. Judging by its appearance, it was probably made by the same factory that manufactured the Soundstream Street Hopper.
It is shaped like a bazooka, and measures 19" long, 9-5/8" tall, and 8-5/8" deep. Dolphin says it weighs 25 lbs, but they must have been smoking something, because it only weighs 9.5 lbs according to our scale. Anyway, the first thing you notice is the very attractive LED lighting, which uses "glow cords" hidden inside the unit. These lights beat to the music, and can be set to 7 different colors, or simply shut off. There is also a light on each side of the speaker, and those lights cannot be shut off. And they do not beat to the music, they beat to a fixed pattern, almost like an SOS signal.
Bazooka-shaped speakers like this usually have 4 plastic legs (or no legs at all), but this model also has 2 steel bars between the legs, covered with foam rings that help protect your table from scratches. This is a nice touch, and we wish more manufacturers would do it.
Dolphin says it makes 1000 watts, but that's a joke. 
In fact, the label on the back says it consumes only 60 watts. And you cannot create more than you consume. 
There are 4 speakers (2 on the front, and one subwoofer on each side). Judging by the sound and the weight balance, we're guessing the sub on the right is a real powered sub, while the one on the left is just a passive radiator. But we haven't disassembled it to verify this. Regardless, the front speakers produce most of the sound. The side speakers don't start vibrating until you crank it up pretty loud, and even then, the amount of visible excursion is very limited. We don't think the bass will satisfy the typical customer of a device like this, who tends to be young and listens to hip-hop. And that's a shame, because it does provide nice mids & highs. If it had adjustable bass, or at least some kind of EQ settings, it would help.....But it doesn't.
Music sources include Bluetooth, USB, FM radio, 3.5mm line input, and microphone input. I found that the line input provided the best sound quality, because I could use my phone's EQ settings to increase the bass. Perhaps your phone can do that while using Bluetooth, but mine cannot.