Two 4-ohm subs will be either a 2 or 8 ohm load, or two 4 ohm loads. For that application, a monoblock amp such as the Xtant A6001 or x1001, PPI PC1800.1, or JL Audio 1000/1 would be "perfect". There are many mono amps on the market, most of them quite good. Look for one that puts full power to a 2-ohm load, not a competition amp that max's out into 1-ohm or less.
I wish amps worked into my 4-ohm world, they could and should, but that's not the reality.
Hope this helped!!