Yes, you can. However, Xero Inventory cannot handle complexity of tracking Amazon Inventory beyond 5 or so items. The SKUs have to be exactly matching and any new SKUs in Amazon need to be manually updated in Xero Inventory. Xero is limited on the number of figures in the SKU whereas Amazon is not. We have seen Amazon will create SKUs in certain circumstances and this can prevent settlements from importing to Xero until the new items are entered.
Because of the less automated elements of the processes involved with Group Sales by SKU, it is not as easy to manage if you have more than 5 SKUs.
Group Sales by SKU is a setting that can be found in A2X Settings>Invoice Settings.