In a multichannel information system, users can access the same service through different channels. At a high level of abstraction, "channel" examples are: a simple PC connected to the service provider through the Internet, a PDA connected through a wireless LAN, a SmartPhone exploiting UMTS and a private backbone. Within an adaptive multichannel information system, the system is also capable of tuning itself according to the user needs, underlying network and computing infrastructure. We present a novel quality model for multi-channel e-Services and we propose adaptation strategies that allow describing and enforcing QoS aspects, respectively. In particular the quality model, which can be viewed as an extension of existing proposals for single-channel system, allows classifying resources of a multichannel information systems, their properties related to non-functional quality related aspects, and defines the role of the service provider as a proposer of service levels, and of the user as a selector of the adequate service levels.