Go with the X1 !
The output impedence of the x1 preamp is 200 ohms unbalanced, 750 ohms balanced. The x350 has a 22Kohm input on balanced.
I have owned pass labs aleph 2 amps, the aleph P, and the X1. The X1 is so far the best solid state preamp I have used. It has that rare sense of 'air' that I had previously only heard from a tube preamp. It matched beautifully with the aleph 2's. I have used several other preamps with the alephs, but none matched as well. In fact, I have never heard so much synergy from a matched component set.
It's also a great looking preamp.
The output impedence of the x1 preamp is 200 ohms unbalanced, 750 ohms balanced. The x350 has a 22Kohm input on balanced.
I have owned pass labs aleph 2 amps, the aleph P, and the X1. The X1 is so far the best solid state preamp I have used. It has that rare sense of 'air' that I had previously only heard from a tube preamp. It matched beautifully with the aleph 2's. I have used several other preamps with the alephs, but none matched as well. In fact, I have never heard so much synergy from a matched component set.
It's also a great looking preamp.