Amplifier upgrade for Kef Reference 4c trio

I recently took the leap to make a major upgrade to my living room (17' x 17' x 10') audio quality and jumped on the current KEF promotion to get a trio of Reference 4c as part of a larger 5.2.2 setup that is doing dual duty as an HT and a 2-channel system. I had previously been about to pull the trigger on the Reference 3/Reference 2c set based on some broad-ranging speaker auditions, so I knew what I was getting into from a general sound perspective  Despite the oddity of using what's technically a center channel turned on end, they have been an astonishingly good sound, and I couldn't be happier with what I'm getting from them, from a 2-channel or a HT system perspective. They also look quite attractive in rosewood, if I may say.

The challenge I'm currently having is that I am not sure my current amp, an NAD M27, is going to be up to the task of driving them. The Reference 4c are nominally rated at 8 ohms and 90dB, but their impedance can go as low as 2.9 ohms (per the recent ASR review), and KEF recommends amplifiers with power ratings of 50W - 400W for them. If I understand the rule of thumb math correctly, the amplifier for the front LCR should be in the 240W to 440W range, or greater, and the M27 just can't quite cover that.  With stereo amps, there's a wide range of options, but for driving those 3 channels, this power requirement limits my options.  My equipment space limitations mean I really can't fit more than about 10u of amplifiers, and the WAF for this project does not extend to having monoblocks out on the floor, or anything that has exposed tube amplification. The other major consideration is that I need to keep my amplifier budget under about $13k.  For the two-channel side of things, I'm currently using a Legacy Audio Wavelet preamp/DAC/Crossover and a BlueSound Node connected to the Wavelet's USB in. My AV processor is an Anthem AVM 70 which is feeding the front L/R channels to the Wavelet and the rest directly to the M27 amp. To satisfy providing 7 channels and ensuring the front three have adequate power, these are the options I've identified that can work in my space

1. Legacy Audio iV3 Ultra paired with either the existing M27 or an iV4
2. Bryston 21B^3 paired with the M27 (this handily beat out the McIntosh MC303 in a back to back listening test with some Contour 60i speakers, so I've stricken the latter from the list of options)
3. 3x Benchmark AHB2 as bridged monoblocks paired with the M27
4. 2x Parasound Halo A51, bi-amping the front LCR and using the remaining 4 channels for the surrounds
5. 3x PS Audio M700 monoblocks paired with the M27

Have I missed any viable options here?  If so, what might they be?  If not, are there any of these combinations that are likely to significantly outshine the others given the speakers they'd be powering?

Thanks,