Multi-channel MACs have recently attracted significant attention in wireless networking research because they possess the ability to exploit multiple frequency bands in order to increase the capacity of wireless ad hoc networks. A number of multi-channel MACs have been proposed in the last few years. However, these protocols rely on two rather impractical assumptions: low channel switching latency and fine-grained clock synchronization. This paper presents Asynchronous Multi-channel Hopping Protocol (AMHP), a multi-channel MAC protocol that does not build on these two impractical assumptions. We conduct an extensive performance evaluation and compare AMHP with 802.11 MAC, Asynchronous Multi-channel Coordination Protocol (AMCP), Multi-Channel MAC (MMAC), and Slotted Seeded Channel Hopping (SSCH). The major findings of our performance evaluation are: (1) all multi-channel MACs underperform 802.11 MAC at low load but AMHP comes very close to 802.11 MAC's performance at this load, (2) all multi-channel MACs give better performance than 802.11 MAC at medium and high load, (3) SSCH attains good results in one-hop scenarios or at low loads but loses its effectiveness at high loads and in multi-hop scenarios, and (4) AMHP outperforms all other multi-channel MACs at all loads.