I use LTC2664 in my developments. I need to receive Vout= +-2.5 V on 2 channels. To acheive it I must tie MSP1 pin to Vcc?
Yes, If you want the part to have a span from -2.5 to 2.5V you need need tie MSP1 to Vcc and the other MSP pins to GND as per this table:
The part will then reset to mid scale. Then you can program the LTC2664 to whatever code you want between -2.5V and 2.5V