I use the KV3 with my Kg4s. I haven't tried either of the 2.2s or 2.5s. I have tried the KLF-C7 which sounded to me as though the sound was going over my head (literally). The KV3 was much smoother in my system. I also have a C1, C2 and C3 which I believe are from the Synergy line. To me, the C3 sounded OK, but not as good as the KV3.