The Mmats HIFI6150d. I am absolutely over the moon with this little upgrade. What a fantastic amp and company to deal with. They overnighted me the amplifier and I just finished putting it in the truck. My first impressions have blown me away. Although I have only put a little time into re-tuning my vehicle, I am just floored by the sound being produced.
I have this installed in the cab of a truck too and have not noticed the fan noise. Its much quieter than my S1+ monoblock fan. Plus I have them in an enclosed trough with some clever venting to help minimize any unwanted airflow sounds. All in all, I can't say enough good things about my Mmats experience so far. I look forward to replacing that S1+ with something from the Mmats lineup, as I am now a huge fan of the brand!
I will try to post some installed pics when I get a chance this weekend. Cheers!