The classroom is approximately 40 x 50 feet . It is a brick and mortar room , no thermocol or any other acoustic material . Students per class is 30 . Why do you think investing in 4 . 1 is wasting the money . <| sep |> Just a random observation , that I hope is nothing . After using the Amex Plat link yesterday and getting approved , I noticed the last 4 or 5 purchases on my Delta Platinum have been moved back into Pending after actually posting to my statement . I wonder if that means they ' re scrutinizing accounts of leaked link users ? They were all legit so I ' m not worried . <| sep |> More importantly than that is the kind of DAC you have in your phone . If you want good sound quality in your phone , get one with a good dac . I can ' t tell much of a difference between , let ' s say shuttle that uses android built in audio and gmmp custom audio engine using ear buds . Most fanboys of these music apps will say that it ' s a huge difference , it ' s not . It ' s more of a generic answer to praise the app . I ' m using gmmp and also shuttle on a regular basis . The difference is mostly that gmmp has much more settings and customization than shuttle . Oh , and gmmp used less ram as well , which is always a plus on an older device like mine .