What would be helpful is a shasum of the phoenixminer binary. I am using 5.5c downloaded from this thread a while ago, with the right checksum. This is the linux version. My Phoenix miner binary has:

user@miner$ sha256sum PhoenixMiner

6de6285d944981576862c960dfa917bbd4f72c5fac45f0b2880c560c89f12e81  PhoenixMiner

If somebody could do the same for Windows (non-nicehash binary, but 'official' download) we have something to compare the nicehash binaries to. Just an idea