42dB ~ 16W !!!
where is coming that 42dB???
Wireless specification for DISC Lite5 ac is tx power max 25dBm @ 6MBit/s (22dBm for chain) and 18dBm @ MCS9 (15dBm for chain)
If you do not use "superchannel", you can't lie about antenna gain, if specified, are ignored: DISC Lite5 ac has integrated antenna with fixed 21dBi gain (18dBi for chain.
on "non-superchannel" max tx power is 9dBm (30dBm max - 21dBi), more appropriate: 6dBm for chain 0 and 6dBm for chain 1
the 30dBm max is defined inside RouterOS, use this command to check (in this example on 6.46.8 and 6.47.9)
/interface wireless info country-info "united states3"
but.. if the device can transmit to 25dBm (@6MBit/s) + 21dBi = 46dB... the device "Max power consumption" is 7W and transmit near 40W???...
I'm Italian, not English. Sorry for my imperfect grammar.