This may just turn into a rant. The standard 19" rack unit is still a perfectly good way to manufacture bass amps. Except for some reason most Class D amps. Many class D amps are about the same size and shape. Roughly 2U tall by 'half U' (though many are too wide to sit 2 wide in a 2U case) wide. Did or does something inside determine this is the proper size? They don't all have a fan, so it's not that they have to be tall enough for a square fan port at the rear. Yes, rack ears are available for some class D that I have looked at, which acknowledges that the standard rack size is still important for a modern product to be used but doesn't really explain why not just make the amp fit in 1U to begin with. My expectation is most of these amps could have been built into a vented top 1U chassis, give more room to spread out multiple smaller heatsinks or more surface area for a larger one to be passively cooled. Other than being able to sit atop a 210 cab stood vertically is there really much benefit to the typical class D form factor? They do look silly on top of something as wide as a 115 or 410 let alone an 810, while a rack case, regardless how tall looks a lot less silly. So here is my thought process. Many of the early Class D amps are offered in 250-350W and 450-550W the higher choice. Now many of the 450-550W are being replaced by 700-800W versions. If each of these were 1U instead of their taller designs, I could buy a new 1U with a beefier power section and have 2 different sounding preamps and 2 different power rated power amps in a 2U case. Now you don't need to sell your MB500 if you need more power, you can get a Darkglass 900 to go with it. (also, why do none of the Tonehammer amps have an effects loop?) Not often do I get to crank an 800W amp, but some of them do have an interesting, not unpleasant type of power distortion. If I want that sound but it's too much power, I can use the lesser of the power amps available in its sweet spot instead. These do sit in (sometimes very narrow) sweet spots though, hence having 2 at different power ratings gives more of a versatility that's still both light and relatively small. It also means you could use existing, already industry standard 1U preamps with your new class D amp's power section without it looking ridiculous or having to buy a dedicated power amp. Let's say a 4U shallow case with 4 total preamps and 2 total power amps, mixing and matching old and new, tube pres and full ss amps, etc. or subtract a pre and add a wireless, or whatever. And probably amps + case still be under 30lb. Further, if manufacturers standardized a rear vent location, an external fan could be mounted cooling through both vents because they are stacked making a square out of two rectangular vents. For how many years have bass amp heads been manufactured within 1-2 inches of the same width? Why go away from all that now? All of this means nothing without a time machine. But it would be nice going forward if they would standardize on a 1U tall size, that a standard set of rack ears could be made for any future heads to use in common. And yes apparently it has become a rant. I apologize to you all.