Assume an employer has a DB Plan and PS plan that covers the same employees in both plans.
Covered Compensation is $1,000,000.

The DB minimum under 430 is $300,000
The DB maximum under 404 (assiming no DC Plan) is $500,000

Can the sponsor contribute the $500,000 to the DB and also contribute 6% of pay $60,000?

Are they limited to $300,000 to the DB and also contribute 6% of pay $60,000?

Would they be able to contribute $500,000 to the DB but nothing to the DC?

You said the plan covers "employees" so I'm assuming it's a PBGC plan. Didn't PPA exempt PBGC plans from 404(a)(7)?

Good point. On the PBGC covered small plans which is what I'm running into here.

I found some additional discusion on this in the 401(k) section of the forum http://benefitslink.com/boards/index.php?showtopic=40008

That indicates that even for small non-PBGC plans it looks like you can deduct the maximum to the DB and the 6% to the DC.