That's true. There is a difference related to marine. The Arc Audio KS series (a very solid amplifier) has the heat sink on the interior and is dependent on fan cooling. This means there is a constant flow of moist air flowing over a raw circuit board. It's not a concern in automotive but a long term corrosion consideration in marine. The Wetsounds Syn series shares this design although the Wetsounds has a conformal coating to protect the board. For this reason I recommend the Wetsounds amplifiers.
On another note, it is easy to test the true amplifier power if you have a large enough power supply. And, we have 200 amps of power supply on our bench backed up by two group 31 AGMs. You might be surprised to discover how many name brand amplifiers do not come close to their factory power ratings. The Wetsounds amplifiers have consistently tested as honest.
Also, the Syn and SD series are designed in this country by Robert Zeff. That has become extrememly rare. Most mobile electronics companies are simply importers, accepting what Asia feeds them with little understanding as to what is in the chassis.