Hello Pete: It's been so long since I've wanted to use the BSC, but I've finally built it this weekend for my New Large Advent speakers. I went with the 4.7K version and 6dB. I have it on the tape in and out on my Sansui amp, and the improvement was well worth it. I noticed an improvement with a single pair running and in the stacked setup. Thanks so much for all your efforts on this. I now want to build the single toggle switch version with 4dB, 5dB and 6dB for comparison, then settle on the one I like best. I just reviewed your earlier post and your notes and I have a question before I proceed. The values you listed in post #112 for the single toggle version don't match either of the 2.2 or 4.7k version values. Is this an error, or is it correct and the values for resistors and caps change because of the design for the single toggle version? Your comments below on the toggle switch version: Build it for 4dB of BSC, which has a shunt R of 7.5K, C of .047 uF One switch side gets 22K in series with .01 uF to ground, one for R another for L, this is +5 dB, Other switch side gets 10 K and .022 uF to ground, one for R another for L, this is +6 dB, Center off pos is +4 dB. HF boost just switches in the .0047 uF cap. 4.7K Version: R1 = 4.7 K, C1 = .0047 C2 R2 4dB .047 7.5K 5dB .056 5.6K 6dB .068 4.3K <– this is what I currently went with. Which values should I go with for the 5dB and 6dB resistors and caps? I see the 4dB values are the same for both versions. Thanks again, Bill