I am using 1.3SEs with a SimAudio I-5 with great success for the past year.
It does not appear that my I-5 is underpowering the 1.3SEs. This may be for two reasons - I'm listening in a medium-sized (not small) room and the I-5 is relatively high-current.
If you want to stay closer to the 1000 price point, consider the I-3.