@Mostropovich 

My suggestion would be to set up a bank account in QB called "Clearing Account" and use that as the adjustment account.  A bank clearing account comes in handy in many instances in accounting.  One other thought: you don't need to make two separate inventory quantity adjustments, you can put both products on one adjustment (i.e. Line 1 is product ABC-a with a -10 adjustment Line 2 is product ABC-b with a +10 adjustment).  Just my $.02.

Edit:  I failed to mention you can select 'Cash on hand, Checking or Savings' for the Tax form section when creating the clearing account.  It really doesn't matter since you always want to make sure the balance in the clearing account is $0 after the adjustments.