Peachtree integrateds sound fine on Zu speakers, though better on the 12+ ohms speakers than the 6 ohms Definition configurations. "Fine" being the operative word. That is, for their cost Peachtree integrateds are beyond reproach. If you can afford more, by all means put more money into your amplification for more engagement, presence, musical intimacy and more convincing recreation of the recorded event. It will be quite worthwhile. You will get no-apologies, serviceable fidelity out of Peachtree + Zu, but you'll be leaving quite a lot of the speaker's musicality, involvement and sonic potential untapped. Peachtree is far less than optimal, and far more than objectionable, the classic mid-fi dilemma as to where you put your cash.
As I've written many times before: going lighter on the Zu speaker (lower in the line) and pushing more of your cash into exceptional amplification is generally the better route with Zu if funds are constrained and you have a set total spend allowed.
Phil