As their “iBT” names suggest, iBT4 and iBT25 are both part of iHome’s growing lineup of Bluetooth speakers, featuring dead-simple wireless pairing for iOS devices and the latest iPod nano. iBT4 is based heavily on the design of iHome’s earlier iP4, a twin-speaker boombox with a deliberately plasticky, flat-colored look, but achieves a considerably smaller size of 7.75” wide by 9.6” tall by 4” deep at its largest…