Threshold input impedance ????

Thanks for you reply. The reason behind my question is that I am planning on buying a pair of MIT balanced interconnects and they are input specific (Low/Medium/High) and I need to pick the right one. Here is how MIT devide them: low (5-50-kW), medium (40-100kW) or high (90-¥kW) .

Thanks Gonzalo. I was very happy with the S450e but I had the opportunity to buy back a S550e that I owned a few years ago. That's the only reason I am selling the S450e otherwise it will stay with me for long time. The S550e has sentimental value for me so I couldn't resist to get it back.