Some time ago I bought a small portable speaker (i.e. one with a battery), which is used to play sound from my laptop or phone, and occasionally a TV set. I was looking for good middle and low frequencies. Before the purchase, I compared in one of the stores several devices of this type: Marshall Kilburn II, JBL Charger 4 and Xtreme 2, Sony XB43 and XB41. The test consisted in playing music from two phones connected via Bluetooth to two different devices at once. The same song was played, more or less in half, and subjectively Marshall did the best job for me. An additional advantage is the fact that it does not shine on the front, and the construction seems to be very good quality.
