Hi can someone help me with making of my speaker. Two months ago I ordered this amplifier and bluetooth module (http://www.ebay.com/itm/131695054275?_trksid=p2055... ; http://www.ebay.com/itm/400994683240?_trksid=p2055... )

I have a battery with 3.7 v and then I ordered step up converter (http://www.ebay.co.uk/itm/MT3608-2A-DC-DC-Voltage-... ). The speakers are this 20w ones (http://www.ebay.com/itm/152230288064?_trksid=p2055... ). When I tried to play something atr low volume it was playing it very well but when I tried bigger volume it started interrupting a lot so you could not hear the song. Then I ordered new amplifier (http://www.ebay.co.uk/itm/252428143559?_trksid=p20... ) which has the same problem. Can somebody help me please???

Thanks for all answers, Enej