You need get the 456, A VERY NICE CX by the way, or passives.
The Amp is not good for CX point you need.
Depending on which Vifa's you have, you will want a 2500 Hz to 3500 Hz CX point. Some Vifa's peak and roll off above 2500 Hz.
Still Most tweeters can't play below 2500 Hz.
The amp CX is not going to give you such CX points.
Anthony B. Davis
2Deep2 Silver SVT
2002 IASCA SQ Ult Ama 601+ World Champion runner up
2002 SLAP dBQ Champion

2000 USAC SQ World Champion
2002 USACi SQ World Champion