I think focusing on doubling is somewhat misguided. If an amp is stable and low distortion into 2 ohms it should be fine. How much power can it put into 2 ohms? An amp that can put 300w/ch into 2 ohms can put 150 into 4 ohms and 75 into 8. Whatever it can put into 2 ohms is what matters rather than doubling.
With the 3.7s it's hard for me to imagine they need a huge amp. They're 90db sensitive. (Stereophile measured 90.7.) 2 watts for 93db, 4 for 96, 8 for 99, 16 for 102, 32 for 105, 64 for 108, 128 for 111, 256 for 114. I'd be shocked if these can get anywhere close to 114db before exceeding their physical limits. The fairly inexpensive amps I have do the first 30 watts in class A. I'd bet that pretty much all of my listening is in class A. I worry about bottoming out the drivers a lot more than the amps.
With the 3.7s it's hard for me to imagine they need a huge amp. They're 90db sensitive. (Stereophile measured 90.7.) 2 watts for 93db, 4 for 96, 8 for 99, 16 for 102, 32 for 105, 64 for 108, 128 for 111, 256 for 114. I'd be shocked if these can get anywhere close to 114db before exceeding their physical limits. The fairly inexpensive amps I have do the first 30 watts in class A. I'd bet that pretty much all of my listening is in class A. I worry about bottoming out the drivers a lot more than the amps.