Is there a good, marine, standard size, Head unit radio that has a built in amp? Not looking for a separate amp. Not looking to break the bank either.

Most standard din size radios put 25-50 watts per channel. Two things to consider-blue tooth, and expandable. I just have a cheap kenwood but was able to slowly upgrade in steps due to having line outputs.

If I was to get a new head unit, I'd probably go with a Fusion. They have 4x50 watt built in amps
https://fusion.factoryoutletstore.co...gitemid=497188

No head unit has a GOOD built in amplifier. None, zero. The space and current draw limitations prevent it from being possible. 50 watts per channel is a marketing term, not a real measure of power. The Fusion RA70 is a great unit and they offer a kit to mount it in a standard size DIN hole (as it is a smaller body unit). But I always, always recommend a proper amplifier in a boat.

If you want good sound from a head unit, I recommend you look at getting the absolutely highest sensitivity speakers you can find. The sensitivity is a measure of how much sound (dB) is created with 1 watt at 1 meter. Every 3dB of volume increase will require double the power, so if you start with a cheap speaker with a sensitivity of 80dB then 50w will only get you to a peak of ~97dB, but if you start with nice speakers that have 92dB sensitivity then you will get up to 109dB.

More information:
https://www.lifewire.com/speaker-sensitivity-3134850
A handy calculator:
https://myhometheater.homestead.com/splcalculator.html

Just realized I necro'd an old post, oh well, maybe it will help someone else.