I managed to find a second hand pair on trade me for a very reasonable price, bloody great little speakers! I have no complaints about them.
At a glance they are noticeably smaller than 6c's. But instead of giving vague estimates, grab a tape measure and check the difference.
222 (H) x 152 (W) x 184 (D)
361 (H) x 270 (W) x 210 (D)
Looks like the AV are a fair bit smaller all around, and I must say they give very good sound quality for the price point and size.