When Revel revamped its highly successful 10-year-old Ultima line as the Ultima2, the Lexicon people needed come up with new high-current amps that can drive difficult loads. Say hello to the ZX-7 ($7999), RX-7 ($5999), and GX-7 ($2999). The biggest gun delivers 300 watts times seven into eight ohms, 450 watts into four ohms, and is stable down to two ohms. Oh, and make sure you've got a dedicated 20-amp circuit to run it.