How do you connect the LS17 with the Phi 200? INTERCONNECTS. Interconnects in the signal chain have potential to add distortion, noise, etc., etc. Are also an added expense and a potential limiting factor in your system.
Which preamp/linestage is better? LS17? No; Built into VAC? YES. Also better synergy VAC:VAC.
I have a good friend that has the Sigma 160 integrated and loves it.
Hopefully this explains my comments a little better for you.