So you don't want to use the iPad anymore and instead want to use a Chromebook? In either case, which DAC would you be using or more specifically, what kind of inputs does the DAC have... SPDIF, AES/EBU, USB?
If you already own suitable amp options for the speakers you are using in the shop, then don't buy an amp, just get a streaming source that can connect to a DAC (that you hopefully already own) which in turn connects to an amp/preamp (that you already own).
Doesn't the Tidal app for iPad simply connect to the music in the cloud? In other words you don't actually need your PC running, just stream directly from the internet/cloud to the iPad, isn't that what you are currently doing, or have you downloaded a bunch of content for "offline" listening, and that content is being stored on your PC?