SO I use the 40 for 1 month and am fully satisfied, compared to other adaptive HF system is one that fits the more micro, cel remains discreet in performance, nothing wrong, may be that my microphone (Shure 565 SD Behringer XM8500) are more sensitive to feedback, but nothing catastrophic. who can not afford to invest in the Shure or Sennheiser HF, yes I do it again this choice.