I realize this thread is a bit old, but I have listened to both the W4S and the Pass XP-10 in the same system. I was initially interested in the W4S because the buffer / active design seems well thought out. Unfortunately, I found the sound of it to be quite thin even in comparison to another buffer (the Pass B1 buffer).
I found I liked the performance of the Pass XP10 better than both the W4S and the B1 buffer. It is very transparent in the mid-bass and midrange, with better control in the low bass and better presentation in the high frequencies. I will point out that the amps I use have a very low input impedance, and finding a good matching preamp is tough.
Alan
I found I liked the performance of the Pass XP10 better than both the W4S and the B1 buffer. It is very transparent in the mid-bass and midrange, with better control in the low bass and better presentation in the high frequencies. I will point out that the amps I use have a very low input impedance, and finding a good matching preamp is tough.
Alan