You may have a bit more headroom if you are bi-amping with four 400 series amps, but the 33H (and 33) use power regeneration, and feature better parts quality than the roughly half the price 400 series (the 33H and 33 were designed and made at the zenith of the two-channel market in the mid/late 90's -- Madrigal, like most other manufacturers trying to survive and profit in a market that is now 90% home theater, moved to more affordable, more compact, home theater-friendly amps with the 400 series). If your system is primarily used for home theater, then there is no need for 33H's. On the other hand, if your system is primarily for music, the 33H should be better.
I run my Salons with 130 watt/channel triode tube amps (VAC 140/140 Mk. III's). The best sound I have ever heard from Salons is my friend's pair, which is powered by CAT JL-1 Limited Edition tube monoblocks. Of course, very few tube amps will drive Salons properly due to their low impedence in the bass -- solid-state is much safer with these speakers.
I run my Salons with 130 watt/channel triode tube amps (VAC 140/140 Mk. III's). The best sound I have ever heard from Salons is my friend's pair, which is powered by CAT JL-1 Limited Edition tube monoblocks. Of course, very few tube amps will drive Salons properly due to their low impedence in the bass -- solid-state is much safer with these speakers.