I use X2's with 33's. I consider them to be the best overall amplifier for the speakers. DW uses 33's at home and can use anything he wants so draw your own conclusions.
BTW mine are the ultra high current version 240v 30amp and I have installed them with dedicated individual circuits and ground spike so they are not on the house earth loop. I also have recently used them with Transparent's Power Isolator XL's which given that the 33's regenerate their own power internally shouldn't make any difference, well they do and it's not subtle. I recommend you try them.
Also with the X2's make sure you use the 28.6 ohm woofer damping resistor and not the 32 ohm that the X2 ships with. Both are in the tool kit so its easy to swap them over.
BTW mine are the ultra high current version 240v 30amp and I have installed them with dedicated individual circuits and ground spike so they are not on the house earth loop. I also have recently used them with Transparent's Power Isolator XL's which given that the 33's regenerate their own power internally shouldn't make any difference, well they do and it's not subtle. I recommend you try them.
Also with the X2's make sure you use the 28.6 ohm woofer damping resistor and not the 32 ohm that the X2 ships with. Both are in the tool kit so its easy to swap them over.