With 93db efficient speakers, I question the need for another amp - much less a conversion to monoblocs on top of that. (You do realize you can use two stereo amps on a pair of speakers without converting them to monoblocs.)
IMO, you would be better served allocating that money to upgrading your existing .5 to the max - Rev A Gold. In particular, you can now get the Plitron toroid transformer for the .5 which significantly improves bass performance (among other things) and makes the .5 seem even more powerful. Also, I would strongly suggest the soft recovery diode upgrade. You won't even recognize the sound of your old amp after these upgrades.
One other thing. If you still want more power and upgrades, I would stick with adding a .5 versus just getting the bigger models. The primary reason is that shipping a .5 to get upgraded does not require crating and is much less susceptible to shipping damage via regular means. In addition, two DNA.5 probably sound a little better than one DNA 1 due strictly to the traditional benefits of biamping.
IMO, you would be better served allocating that money to upgrading your existing .5 to the max - Rev A Gold. In particular, you can now get the Plitron toroid transformer for the .5 which significantly improves bass performance (among other things) and makes the .5 seem even more powerful. Also, I would strongly suggest the soft recovery diode upgrade. You won't even recognize the sound of your old amp after these upgrades.
One other thing. If you still want more power and upgrades, I would stick with adding a .5 versus just getting the bigger models. The primary reason is that shipping a .5 to get upgraded does not require crating and is much less susceptible to shipping damage via regular means. In addition, two DNA.5 probably sound a little better than one DNA 1 due strictly to the traditional benefits of biamping.