Hi,
Unless otherwise you are adding a DAC in the Integrated setup it will not sound "SO" good. You have to add a cost/budget for Separate DAC also if you are going with IA.
AVR don't need DAC.
Also if you are going with bigger drivers say 12 incher or 15 incher no need to add sub-woofer, going with small woofers like 4 / 6 inch BS or FS need Sub-woofer too. Most of the bookshelves will have a cut off at 70hz and will not go low.
Regards
Should it be understood, even for a good IA for eg: Cambridge Audio CXA81, which has a ESS Sabre SE9016K2M DAC or the Arcam SA20, which has a ESS 9038K2M Sabre DAC need a desperate DAC ?
Expect such doubts from non-audiophile