Scrum is Enough
Is it possible to adopt agile without technical practices at all? No, it is not. However, it is a less severe mistake than the previous one. If you apply Scrum right, you will inevitably decide to try some technical practices at a retrospective meeting.
The true mistake will be to rely on Scrum solely as a process that will solve all the problems. It can do that, but only if you are open-minded and willing to try various things: from pair programming to BDD. Best coaches believe that Scrum should be adopted in tight pack with XP technical practices. This is a good advice to follow.